This is a very readable review on the exciting, advancing technology of radiation curing. The principles upon which the technology is based, the equipment that is used and the materials which make up a radiation curable formulation are described. The applications of radiation curing are set to expand. Currently, the technology is used in coatings, graphic arts, printing inks, packaging, adhesives, optical and optoelectronic applications, composite production, rapid prototyping, electronics, with liquid crystals, in nanotechnology, for controlled-permeability membranes and hydrogels (including contact lenses), and for the vulcanisation of natural and synthetic rubber. These are all discussed in this review, with principle material types outlined. The review is well referenced to facilitate further reading. It is accompanied by around 400 abstracts from the Rapra Abstracts database, most of which are cited in the text.
There are many possibilities for future developments in radiation curing. The technology permits extensive control over crosslinking, including reversal of the process of adhesion in some cases. This allows the production of release coatings and provides an easy method of removing expensive components at the end-of-life stage. It is also developing a role in medical applications. The prospects for functional and aesthetic coating applications are abundant with pearlescent coatings, liquid crystals in coatings and high gloss coatings, to name but a few. Radiation curing is generally environmentally friendly - dry powder coatings can eliminate the need for solvent-based products, and reversible adhesives can facilitate recycling. Thus legislation is fuelling the drive towards this technology.
What is Radiation Curing? Use of the Terms ‘Drying’ and ‘Curing’ Why Consider Radiation Curing?
The Chemical Processes Used in Radiation Curing
Processes Involving Radicals Processes Involving Carbanions - Anionic Curing Systems
Applications of Curable Coatings Radiation Sources for UV Curing
Initiation of Cure by Photoinitiators Prepolymers Reactive Diluents Pigments Additives
Components of Cationically Cured Formulations Other than Photoinitiators
Reactive Diluents Prepolymers Combinations of Cationic- and Radical-Cured Materials
Applications of Radiation Curing
Wood coating Graphic arts Printing inks Packaging Adhesives Optical Components and Optoelectronic Applications Production of Composites Rapid Prototyping Nanotechnology and Microstructures Liquid Crystals Electronics Powder Coatings Radiation Cured Coatings for Outdoor Use
Water Resistance, Permeability and Hydrogels
Radiation Curing in the 21st Century
Dr. R Stephen Davidson is Emeritus Professor of Applied Chemistry (University of Kent, UK) and Emeritus Professor of Organic Chemistry (City University, London, UK). He has published over 200 research papers as well as being a regular contributor to RadTech meetings. He is a Chartered Chemist (C.Chem.), a Member of the Royal Society of Chemistry (MRSC) and holds two postgraduate degrees.
Dr. Davidson has accumulated knowledge in the general field of radiation curing, relating to free radical and cationic curing systems, the synthesis of photoinitiators, diluents and prepolymers and the development of methods for determining the degree of cure. The development of the analytical methods was crucial for developing an understanding of the mechanism of curing and hence producing simple guidelines for formulators operating with this technology. He has worked with industry on projects such as the UV curing of inks. He is currently a consultant in this field.