Chemistry and technology of agrochemical formulations

483 Pages·1998·23.98 MB·English

by  D A Knowles

Chemistry and Technology of
Agrochemical Formulations
Edited by
D. A. Knowles
FORM-AK Formulation Consultancy Services,
Tonbridge, Kent, UK
Kluwer Academic Publishers
Dordrecht / Boston / London
A C.I.P catalogue record for this book is available from the Library of Congress
ISBN 0-7514-0443-8
Published by Kluwer Academic Publishers,
P.O. Box 17, 3300 AA Dordrecht, The Netherlands.
Sold and distributed in North, Central and South America
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Printed on acid-free paper
All Rights Reserved
© 1998 Kluwer Academic Publishers
No part of the material protected by this copyright notice may be reproduced or
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retrieval system, without written permission from the copyright owner.
Printed in Great Britain
Preface
Agrochemical products and adjuvants are of vital importance in agriculture
to protect food and fibre crops from weeds, insect pests and diseases in
order to feed and clothe the ever-growing population of the world, which is
expected to double over the next 50 years. The total world market for
agrochemical products has been estimated at more than US$30 billion in
1997 and the industry plays an important part in the economies of most
countries.
Enormous changes have taken place in the chemistry and technology of
agrochemicals over the last 20 years or so, and therefore it is timely that a
new book should be published to review the most important areas of
technology and legislation in the research and development of new prod-
ucts, and to describe the current and likely future trends which will carry the
industry forward into the next millennium.
In recent years there have been increasing pressures from governments
and regulatory authorities to produce new agrochemical products which are
safer to the user and have a reduced impact on the environment in general.
Consequently, agrochemical companies and other organizations have been
reviewing their product/pack strategies to provide products which are effec-
tive at low doses and have low toxicity to mammals and other non-target life
forms. There is an increasing trend towards the use of water-based formu-
lations, water-dispersible granules and controlled-release formulations.
Improvements are taking place in safer and more convenient packaging of
products. Spray application techniques are also being developed to improve
targeting on the crop and reduce waste in the field. Effluent treatment and
waste minimization technologies are also well advanced in the factory and
on the farm. New standards are being set to control and regulate the use of
agrochemical products.
The use of surfactants and other additives to give special effects and to
impart long-term product stability is another rapidly developing area of
technology. Surfactant and oil-based adjuvants are also being used to en-
hance the biological activity of active ingredients, either as part of the
formulation or as spray tank additives. These important aspects of
bioenhancement are reviewed and future trends are highlighted.
This book brings together well-known experts from a number of
agrochemical companies, formulation additives and adjuvants suppliers,
consultancies, academic and other organizations with many years of
practical experience of the most important aspects of the chemistry and
technology of agrochemical formulations. One of the aims of the book is to
show how the various technologies are linked together in the development
of new-generation user and environmentally friendly agrochemical prod-
ucts. Future trends in all of these areas are discussed fully and should
provide the basis for safe technology into the next millennium.
This book would not have been possible without the cooperation of a
wide range of authors involved in the agrochemical business, and I am
indebted to them for their timely contributions, the comprehensive reviews
of their special subject areas and for their insight into likely future trends.
Finally, I would like to dedicate this book to the memory of my wife
Mary who, despite her own serious illness, gave me a great deal of support
and encouragement during the long hours of preparation of the manuscript,
and inspired me to complete it. Sadly, she did not live to see the book
published.
D. A. Knowles
Tonbridge, 1997
Contributors
G. A. Bell
Zeneca Agrochemicals,
Jealott's Hill Research Station,
Bracknell,
Berkshire RG42 6ET, UK
L. G. Copping
LGC Consultants,
34 Saxon Way,
Saffron Walden,
Essex CBIl 4EG, UK
P. D. Curie
Dow AgroSciences,
Crossbank Road,
King's Lynn,
Norfolk PE30 2JD, UK
W. K. de Raat
OpdenKamp Consultancy Group,
Koninginnegracht 23,
2514 AB The Hague,
The Netherlands
C. D. Emmerson
AgrEvo Ltd,
Cambridge Road,
Hauxton,
Cambridge CB2 5HU, UK
A. H. Gregory
Pac-Tech,
Treetops, Scotland Close,
Haslemere,
Surrey GU27 3AE, UK
B. C. Hakkert
TNO Nutrition and Food Research Institute,
Department of Occupational Toxicology,
PO Box 360,
3700 AJ Zeist,
The Netherlands
J. Hartmann
Bayer AG,
Alfred Nobel Strasse 50,
D-40789 Monheim,
Germany
P. J. Holloway
lACR-Long Ashton Research Station,
Department of Agricultural Sciences,
University of Bristol,
Long Ashton,
Bristol BS41 9AF, UK
G. F. Houben
TNO Nutrition and Food Research Institute,
Department of Occupational Toxicology,
PO Box 360,
3700 AJ Zeist,
The Netherlands
S. T. Humphrey
Borregaard UK Ltd,
Unit 16, Ponthenri Industrial Estate,
Ponthenri,
Llanelli,
Carmarthenshire SA15 ITY, UK
K. S. Johnson
EPEC,
78 Pound Road,
East Peckham,
Tonbridge,
Kent TN12 5BJ, UK
D. A. Knowles
FORM-AK
10 The Forstal,
Hadlow,
Tonbridge,
Kent TNIl ORT, UK
G. A. Matthews
International Pesticide Application Research Centre,
Imperial College of Science, Technology and Medicine,
Silwood Park,
Buckhurst Road,
Ascot,
Berkshire SL5 7PY, UK
P. J. Mulqueen
Dow AgroSciences,
Letcombe Laboratory,
Letcombe Regis,
Wantage,
Oxfordshire OX12 9JT, UK
P. Nixon
Novartis AG,
CH-4002 Basle,
Switzerland
S. Reekmans
ICI Surfactants,
Everslaan 45,
Everberg B-3078,
Belgium
I. A. van de Gevel
TNO Nutrition and Food Research Institute,
Department of Occupational Toxicology,
PO Box 360,
3700 AJ Zeist,
The Netherlands
J. M. Wagner
Zeneca Ag Products,
1800 Concord Pike,
PO Box 15458,
Wilmington,
DE 19850-5458, USA
Contents
Preface ................................................................................. xiii
List of Contributors ............................................................... xv
1. Introduction .................................................................. 1
References ............................................................................... 7
2. Review of Major Agrochemical Classes and
Uses .............................................................................. 8
2.1 Introduction .................................................................... 8
2.2 Future Needs ................................................................. 9
2.3 World Markets, 1996 ...................................................... 9
2.4 Sales by Category, 1995 ............................................... 10
2.5 Sales by Crop, 1995 ...................................................... 12
2.6 Sales by Region, 1995 ................................................... 13
2.7 Herbicides ...................................................................... 13
2.7.1 Photosynthesis ............................................. 15
2.7.2 Amino Acid Biosynthesis .............................. 17
2.7.3 Lipid Biosynthesis ........................................ 17
2.7.4 Interference with Plant Hormones ................. 18
2.7.5 Cell Division ................................................. 19
2.7.6 Cellulose Biosynthesis ................................. 19
2.7.7 Respiratory Uncouplers ................................ 19
2.8 Insecticides .................................................................... 20
2.8.1 Organophosphorus Insecticides (OPs) ......... 21

v
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vi Contents

2.8.2 Carbamate Insecticides ................................ 22
2.8.3 Insecticides that Interact with
Neurotransmitter Ligand Recognition
Sites ............................................................ 22
2.8.4 Insecticides that Interfere with Ion
Channels ..................................................... 23
2.8.5 Inhibition of Oxidative Phosphorylation ......... 24
2.8.6 Insect Growth and Regulation ...................... 25
2.8.7 Compounds with Uncertain Modes of
Action .......................................................... 26
2.9 Fungicides ..................................................................... 27
2.9.1 Protectant Fungicides ................................... 27
2.9.2 Protein Biosynthesis ..................................... 28
2.9.3 Nucleic Acid Metabolism .............................. 28
2.9.4 Cell Division ................................................. 28
2.9.5 Sterol Biosynthesis ....................................... 28
2.9.6 Triglyceride Biosynthesis .............................. 29
2.9.7 Chitin Biosynthesis ....................................... 29
2.9.8 Respiration ................................................... 29
2.9.9 Indirectly Acting Fungicides .......................... 30
2.10 Plant Growth Regulators ................................................ 30
2.11 Biological Screening: Discovery and Development
of a New Agrochemical .................................................. 30
2.11.1 Chemical Synthesis ...................................... 31
2.11.2 Biological Evaluation .................................... 35
References ............................................................................... 38
3. Formulation of Agrochemicals ................................... 41
3.1 Introduction .................................................................... 41

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Contents vii

3.2 Conventional Formulations ............................................ 43
3.2.1 Granules (GR) .............................................. 43
3.2.2 Solution Concentrates (SL) .......................... 44
3.2.3 Emulsifiable Concentrates (EC) .................... 45
3.2.4 Wettable Powders (WP) ............................... 46
3.2.5 Suspension Concentrates (SC) .................... 47
3.2.6 Seed Treatments (DS, WS, LS, FS) ............. 49
3.3 New-Generation Formulations ....................................... 50
3.3.1 General Trends ............................................ 50
3.3.2 Oil-in-Water Emulsions (EW) ........................ 51
3.3.3 Suspoemulsions (SE) ................................... 52
3.3.4 Microemulsions (ME) .................................... 53
3.3.5 Controlled-Release Formulations ................. 53
3.3.6 Water-Dispersible Granules (WG) ................ 55
3.3.7 Formulations Using a Built-In Wetter ............ 56
3.4 Surfactants for Agrochemicals ....................................... 57
3.4.1 General Characteristics ................................ 57
3.4.2 Adsorption and Surface Tension ................... 59
3.4.3 Micellization ................................................. 61
3.4.4 Kraft Temperature and Cloud Point .............. 61
3.4.5 Wetting and Contact Angle ........................... 61
3.4.6 Particle and Droplet Stabilization .................. 62
3.4.7 Wetting Agents ............................................. 63
3.4.8 Dispersion .................................................... 64
3.4.9 Emulsification ............................................... 65
3.4.10 Solubilization ................................................ 66
3.4.11 Bioenhancement .......................................... 67
3.4.12 Conventional Surfactants ............................. 67
3.4.13 Recent Surfactant Developments ................. 70

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