Light Stabilizers for Coatings

by Andreas Valet, Adalbert Braig

Overview

The durability of coatings is one of the most important quality characteristics and can be achieved by incorporating light stabilizers in the paint. These substances are comprehensively described in this book, which also deals with chemical and applicational aspects.

Product Details

ISBN-13:	9783866301320
Publisher:	Vincentz Network
Publication date:	04/01/2017
Series:	EUROPEAN COATINGS library
Sold by:	Readbox
Format:	eBook
Pages:	156
File size:	14 MB
Note:	This product may take a few minutes to download.

Table of Contents

1 Introduction 11 2 Light and photo-oxidative degradation 13 2.1 Light 13 2.1.1 Photo-physical processes 15 2.2 Photo-chemical degradation processes 16 3 Stabilization options 21 3.1 UV absorbent pigments 22 3.2 UV absorbers 23 3.2.1 UV absorber classes 24 3.2.2 Mode of action of UV absorbers 27 3.2.2.1 Phenolic UV absorbers 28 3.2.2.2 Non-phenolic UV absorbers 30 3.2.3 Examples of UV absorbers 30 3.3 Free-radical scavengers 36 3.3.1 Antioxidants 36 3.3.2 Sterically hindered amines 38 3.3.2.1 Mode of action of HALS 42 3.4 Quenchers 45 3.5 Peroxide decomposing agents 46 4 Stabilization of coatings 49 4.1 Automotive coatings 51 4.2 Light stabilization of automotive coatings 52 4.2.1 Two-coat systems 53 4.2.2 Specific requirements of UV absorbers in coatings 55 4.2.2.1 Solubility and compatibility of UV absorbers 56 4.2.2.2 Volatility of UV absorbers 59 4.2.2.3 Reactable UV absorbers 61 4.2.2.4 Effect of UV absorbers on coating colour 63 4.2.2.5 Unwelcome side reactions 64 4.2.2.6 UV absorbers and photoinitiators 67 4.2.3 Specific requirements on HALS in coatings 71 4.2.3.1 Solubility and compatibility of HALS 71 4.2.3.2 Volatility of HALS 74 4.2.3.3 Reactable HALS 75 4.2.3.4 Effect of HALS on coating colour 76 4.2.3.5 Unwelcome side reactions 77 4.2.4 Weathering results for two-coat systems 79 4.2.4.1 Weathering tests 79 4.2.4.2 Results for solvent-borne clear coats 86 4.2.4.3 Results for water-borne clear coats 97 4.2.4.4 Results for powder clear coats 100 4.2.4.5 Results for UV-curable clear coats 103 4.2.4.6 Coatings on plastic substrates 106 4.2.4.7 UV protection of epoxy-based fibre reinforced plastics 111 4.2.4.8 Effect of additional basecoat stabilization 114 4.2.4.9 Exposure results for one-coat finishes 117 4.3 Light stabilization of industrial coatings 121 4.3.1 Stabilization of paints for metal substrates 122 4.3.2 Stabilization of clear wood coatings 125 4.4 Stability of light stabilizers 128 4.4.1 Photo-chemical stability of UV absorbers 128 4.4.2 Long-term stability of HALS 137 5 Conclusions 141 6 References 143 Authors 151 Index 153

Preface

Almost twenty years after the first edition of this book, the editor was asked by colleagues in the coating industry whether it would be possible to publish an up-dated second edition. When the editor asked us whether we would be interested in working on such a second edition, we agreed with great pleasure. Although some time has passed since the first edition, the problems facing the industry are still the same: paint flaking off an object remains a serious concern. The object has lost its protection and is exposed to the elements. It has lost the colour that made it attractive. It has become insignificant and unnoticed. The purpose of this book is to explain the underlying principles of paint degradation, demonstrate, with the help of numerous examples, how paint films can be protected and serve as a practical guide for formulators when selecting light stabilizers for their paint formulation. For a more precise analysis of the mechanism of paint degradation and its prevention, the reader is referred to the extensive bibliography at the end of the book, which covers the subject comprehensively. Hermann Hesse wrote "Blue, yellow, white, red and green - what wonderful colours” [1]. When properly stabilized, colourful finishes ARE wonderful. We would like to take this opportunity to thank our colleagues from the former Ciba Specialty Inc. and BASF Switzerland AG. Without their collaboration and support it would have never been possible to carry out the research, over a period of more than two decades, on which this book is based. We would also to thank Dr. Godwin Berner and Hans-Jürgen Berger who pioneered, built-up and led this successful business for so many years. Special thanks goes to Allan Cunningham for his great support editing our English text. Basle, Switzerland June 2016 Andreas Valet and Adalbert Braig