Coil Coating

188 Pages·2014·12.653 MB·English

by  Sander, Jörg

The Mission: To know everything about coil coatings and how
they can be used successfully, from the basic principle
underlying the coil coating process to substrate preparation,
Emmanouil Spyrou
selection of raw materials, coil coating line equipment, perfor-
mance testing and research topics through to standardisation.
Powder Coatings
To provide a solid grounding in all the important principles of
Jörg Sander
coil coatings – essential for the successful development of can
Chemistry and Technology
and coil coatings.
Coil Coating
The Audience: Formulators seeking to stay abreast of the latest
3rd Revised Edition
developments in can and coil coatings as well as immersing
themselves in the topic, along with experts looking for detailed
information about surface preparation, materials, application,
standardisation and test methods. Anyone involved in the coil
coating manufacturing process who needs a full understanding
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The Value: At last, a highly topical technical book in English a

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on the subject of coil coatings. This comprehensive book od
covers every aspect of the topic in a format that the reader can the
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ISBN 978-3-86630-834-3
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Jörg Sander
Coil Coating
Jörg Sander: Coil Coating
© Copyright 2014 by Vincentz Network, Hanover, Germany
ISBN: 978-3-86630-651-6
Cover: Salzgitter Stahl, Salzgitter/Germany
Bibliographische Information der Deutschen Bibliothek
Die Deutsche Bibliothek verzeichnet diese Publikation in der Deutschen
Nationalbibliografie; detaillierte bibliografische Daten sind im Internet
über http://dnb.ddb.de abrufbar.
Jörg Sander
Coil Coating
Hanover: Vincentz Network, 2014
EuropEan Coatings tECh FilEs
ISBN 3-86630-651-2
ISBN 978-3-86630-651-6
© 2014 Vincentz Network GmbH & Co. KG, Hanover
Vincentz Network, Plathnerstr. 4c, 30175 Hanover, Germany
This work is copyrighted, including the individual contributions and figures.
Any usage outside the strict limits of copyright law without the consent of the publisher is prohibited and punish-
able by law. This especially pertains to reproduction, translation, microfilming and the storage and processing
in electronic systems.
The information on formulations is based on testing performed to the best of our knowledge.
The appearance of commercial names, product designations and trade names in this book should not be taken
as an indication that these can be used at will by anybody. They are often registered names which can only be
used under certain conditions.
Please ask for our book catalogue
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Layout: Danielsen Mediendesign, Hanover, Germany
Printed by: Quensen Druck + Verlag GmbH & Co. KG, Hildesheim, Germany
ISBN 3-86630-651-2
ISBN 978-3-86630-651-6
EuropEan Coatings tECh FilEs
Jörg Sander
Coil Coating
Jörg Sander: Coil Coating
© Copyright 2014 by Vincentz Network, Hanover, Germany
ISBN: 978-3-86630-651-6
European Coatings Tech Files
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“Comprehensive“ and “based on practice“ sum up the aims of the European Coatings
Handbook. The book covers the full spectrum of coatings formulation in a single vol-
ume. Topics range from the underlying chemistry to process engineering, from safety
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parts of coatings composition, application methodology, quality assurance, industrial
health, and safety is highly useful.
Order at: www.european-coatings.com/shop
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Foreword
During my entire business career, I have seen many industrial applications of paints and
coatings to metal, be it on extruded profi les, bicycle frames, escalator steps, car bodies,
wheel rims and automotive trim parts, or beverage cans, to name a few. The most appealing
application for me, however, has always been the continuous coating of metal coils.
Coil coating provides fascinating ways of producing coated metal goods. Highly sophisti-
cated processes and the profi cient and sustainable use of elaborate process chemicals and
materials bring about durable, high-quality painted products. These can be processed to
create a wide range of articles with an abundance of uses, technical features, shapes, and
surface aspects.
This present book is based on the manuscript of a tutorial I held during the European Coat-
ings Conference Coil and Can Coating that was organised by Vincentz Network in Berlin in
October 2011. It is the fi rst comprehensive English-language description of the coil coating
technology available to the public in years. To make the book attractive for the insiders of
the coil coating community and instructive for newcomers to this exciting technology alike,
a good deal of elaboration was needed beyond the conference script. Thus the book embraces
both: A synopsis, maybe also a useful look at the bigger picture for those already conversant
with the subject, and an in-depth introduction for those who want to familiarise with it. In
particular, students of process and equipment engineering, surface science, pretreatment
and paint technologies, but also of architecture and metal design shall fi nd detailed, and, I
hope, popular descriptions, explanations, and interesting connections demonstrated.
I am grateful to many colleagues in the business who helped in discussions and by provid-
ing detail information about their specialist subjects. A particular pleasure was meeting
Dr. Bernd Meuthen, Past President of the ECCA, long-standing President and Honorary
President of the German ECCA Group, and lead author of a German standard publication
on the topic, during my very early days in the business. I have been very much indebted to
Bernd for sharing his profound knowledge and his enthusiasm for coil coating that I have
always admired. The compilation on standards, one of his very particular interests, is based
on his earlier work. Sadly, Bernd Meuthen died on October 24, 2013. And so I feel it fi tting to
dedicate this work to his memory. I hope it helps to inspire and enthuse future coil coating
chemists and engineers as Bernd was able to do.
Velbert, Germany, October 2013
Jörg Sander
Jörg Sander: Coil Coating
© Copyright 2014 by Vincentz Network, Hanover, Germany
ISBN: 978-3-86630-651-6

Contents 7
Contents
1 Coil coating – principle, market and applications ...................................... 13
1.1 Introduction ............................................................................................................................ 13
1.2 Coil coating process .............................................................................................................. 14
1.3 Metalworking with precoated coil ..................................................................................... 18
1.4 Inherent benefits of coil coating ........................................................................................ 19
1.5 Coil coating market in Europe ............................................................................................ 20
1.6 Applications of precoated metal......................................................................................... 22
1.6.1 Overview ................................................................................................................................. 22
1.6.2 Building applications ............................................................................................................ 22
1.6.3 Transport applications ......................................................................................................... 24
1.6.4 Applications in appliance and general industries ......................................................... 25
1.6.5 Packaging applications ........................................................................................................ 26
1.7 European Coil Coating Association, ECCA ...................................................................... 26
1.8 History of coil coating .......................................................................................................... 28
2 Corrosion protection ..................................................................................... 31
2.1 Principles of function ........................................................................................................... 31
2.1.1 Corrosion phenomena .......................................................................................................... 31
2.1.2 Strategies for corrosion inhibition ..................................................................................... 33
2.1.3 Metal oxide formation, passivation and conversion coating ........................................ 34
2.1.4 Cathodic protection ............................................................................................................... 35
2.2 Design of organic coating systems .................................................................................... 35
2.2.1 Diffusion barriers .................................................................................................................. 35
2.2.2 Pigments ................................................................................................................................. 35
2.3 Function of individual coating layers ............................................................................... 36
3 Industrial cleaning ........................................................................................ 39
3.1 Introduction ............................................................................................................................ 39
3.2 Why cleaning? ........................................................................................................................ 39
3.2.1 Contaminations ...................................................................................................................... 39
3.2.2 Cleanliness and surface tension ........................................................................................ 40
3.2.3 Paint adhesion ................................................................................................................................................... 41
3.3 Aqueous cleaning .................................................................................................................. 41
3.3.1 Overview ................................................................................................................................. 41
3.3.2 Alkaline cleaners ................................................................................................................... 42
3.3.3 Mechanism of alkaline cleaning, bath age and control ............................................... 42
3.3.4 Surfactants .............................................................................................................................. 44
3.4 Cleaning physics ................................................................................................................... 46
3.4.1 Influence factors .................................................................................................................... 46
3.4.2 Rinsing and maintenance .................................................................................................... 46
Jörg Sander: Coil Coating
© Copyright 2014 by Vincentz Network, Hanover, Germany
ISBN: 978-3-86630-651-6
8 Contents
4 Pretreatment .................................................................................................. 49
4.1 Introduction ............................................................................................................................ 49
4.2 Substrates ............................................................................................................................... 49
4.2.1 Overview: Particular substrates for coil coating............................................................. 49
4.2.2 Steel .......................................................................................................................................... 50
4.2.2.1 Blast furnace process ........................................................................................................... 50
4.2.2.2 Steel making and refining ................................................................................................... 51
4.2.2.3 Galvanised steel .................................................................................................................... 51
4.2.3 Aluminium .............................................................................................................................. 53
4.2.3.1 Bauxite refining and Al electrolysis .................................................................................. 53
4.2.3.2 Properties of aluminium and its alloys ............................................................................. 54
4.3 Basics of pretreatment technology ................................................................................... 55
4.4 Pretreatments for coil coating ............................................................................................ 55
4.4.1 Alkaline passivation ............................................................................................................. 55
4.4.2 Iron phosphating ................................................................................................................... 56
4.4.3 Chromating ............................................................................................................................ 56
4.4.3.1 Yellow chromating (chromium chromating) ................................................................... 56
4.4.3.2 Green chromating ................................................................................................................. 57
4.4.4 [Ti,Zr]F 2- based processes: Chromium-free pretreatment ........................................... 58
6
4.4.4.1 Basics ....................................................................................................................................... 58
4.4.4.2 Chemistry ............................................................................................................................... 58
4.4.4.3 Conversion layer composition ............................................................................................ 58
4.4.4.4 Performance ........................................................................................................................... 59
4.4.4.5 Architectural application ..................................................................................................... 61
4.4.5 Synopsis: State-of-the-art coil coating pretreatments ................................................... 61
4.5 Recent pretreatment development .................................................................................... 62
4.5.1 Pre-commercial processes .................................................................................................. 62
4.5.2 Primer-pretreatment ............................................................................................................ 63
4.6 Application.............................................................................................................................. 64
4.6.1 Immersion and spray processes ........................................................................................ 64
4.6.2 Alternative application processes ..................................................................................... 64
4.7 Environmental considerations............................................................................................ 65
4.7.1 Legislation............................................................................................................................... 65
4.7.2 Environment: Labelling and emissions ............................................................................ 66
4.7.3 Waste Treatment ................................................................................................................... 66
5 Coil coating paints ........................................................................................ 69
5.1 Definition ................................................................................................................................ 69
5.2 Ingredients: Carrier media .................................................................................................. 69
5.3 Drying and curing mechanisms ......................................................................................... 69
5.3.1 Physical drying ...................................................................................................................... 69
5.3.2 Chemical curing, crosslinking ........................................................................................... 70
5.3.3 Radiation curing systems ................................................................................................... 71
5.4 Powder paints ........................................................................................................................ 72
5.5 Binder resins .......................................................................................................................... 72
5.5.1 Introduction ............................................................................................................................ 72
5.5.2 Polyvinyl chloride, PVC ....................................................................................................... 73
5.5.3 Polyvinylidene difluoride, PVdF ........................................................................................ 74
5.5.4 Epoxy resins ........................................................................................................................... 75
5.5.5 Polyester resins ..................................................................................................................... 76
Contents 9
5.5.5.1 Raw materials for polyester resins .................................................................................... 76
5.5.5.2 Crosslinking of polyesters with melamines .................................................................... 78
5.5.5.3 Crosslinking of polyesters with polyisocyanates ........................................................... 80
5.5.6 Polyurethanes ........................................................................................................................ 80
5.5.7 Acrylic resins ......................................................................................................................... 81
5.5.8 Binder resins: Comparison and uses ................................................................................ 82
5.6 Coil coating paints statistics ............................................................................................... 83
5.7 Roles and classes of pigments ............................................................................................ 83
5.7.1 Introduction ............................................................................................................................ 83
5.7.2 Anticorrosive pigment ......................................................................................................... 83
5.7.2.1 Overview ................................................................................................................................. 83
5.7.2.2 Active pigments – lead and chromate pigments ............................................................ 84
5.7.2.3 Active pigments – phosphate pigments ........................................................................... 84
5.7.2.4 Other active anticorrosive pigments ................................................................................. 85
5.7.3 Barrier and sacrificial pigments ........................................................................................ 85
5.7.4 Colouring and extender pigments ..................................................................................... 86
5.8 Auxiliaries............................................................................................................................... 87
6 Coil coating line equipment .......................................................................... 91
6.1 Cleaning and pretreatment installations ......................................................................... 91
6.1.1 Cleaning .................................................................................................................................. 91
6.1.2 Pretreatment application ..................................................................................................... 93
6.1.3 Advances in plasma technology for cleaning and pretreatment ................................ 94
6.2 Strip travel and planarity control ...................................................................................... 94
6.3 Coater technology ................................................................................................................. 96
6.3.1 Roll-coaters ............................................................................................................................. 96
6.3.1.1 Roll-coater operation ............................................................................................................ 96
6.3.1.2 Coater rolls ............................................................................................................................. 97
6.3.1.3 Control of the roll-coating process .................................................................................... 98
6.3.1.4 Auxiliary equipment ........................................................................................................... 99
6.3.2 Other paint application techniques ................................................................................... 100
6.4 Curing and oven technologies ............................................................................................ 105
6.4.1 Thermal curing ...................................................................................................................... 105
6.4.1.1 Convection ovens .................................................................................................................. 105
6.4.1.2 Infrared and near-infrared curing ..................................................................................... 106
6.4.1.3 Induction curing .................................................................................................................... 108
6.4.1.4 Comparison of thermal curing techniques ...................................................................... 109
6.4.2 Radiation curing .................................................................................................................... 110
6.4.3 Cooling and exhaust management .................................................................................... 111
6.5 Examples of modern coil coating installations ............................................................... 112
7 Performance testing ...................................................................................... 117
7.1 Introduction ............................................................................................................................ 117
7.2 Coating thickness .................................................................................................................. 117
7.3 Adhesion testing ................................................................................................................... 118
7.3.1 Overview ................................................................................................................................. 118
7.3.2 Application tests .................................................................................................................... 118
7.3.2.1 Tests involving deformation ............................................................................................... 118
7.3.2.2 Other adhesion tests ............................................................................................................. 120
7.3.3 Laboratory methods .............................................................................................................. 120