Radiation Curing of Coatings
Reviewed by: Anthony J. Berejka
co-founder and Past-President of RadTech International North America
At the recent RadTech 2002 conference, two books published by ASTM International (www.astm.org) made their debut:
Radiation Curing of Coatings by Dr. Joseph V. Koleske
ASTM Standards Related to Testing of Radiation-Cured Coatings
Both of these books should be in the libraries and collections of those interested in radiation curable materials.
Radiation Curing of Coatings is unlike many other books in this field in that it is a coherent work of an experienced and astute author, Joe Koleske. Other tomes that have come out in recent years on radiation curing and radiation applications are compilations of diverse articles from numerous contributors. As such, these other works highlight some areas, neglect others and have differing points of view, depending upon the contributors, being somewhat heterogeneous collections much like the RadTech conference proceedings themselves. In this easy-to-read 244 page book, Dr. Koleske blends his historical perspective on the development of various aspects of radiation curable coatings technology and in particular chemistry with sound fundamentals on basic reactions not only involved in radiation curing and photochemistry, but also used in the development of materials used in this field.
Chemists new to this area as well as those experienced in radiation curables will find this book an invaluable resource of pertinent information on structures, reactions, and key properties that are given in concise tables. The experienced chemist will also find the extensive references at the end of each chapter to be exhaustive lists of patents and articles tracing the development of this technology from its inception to the present. One finds in almost every chapter a bit of history on the development of radiation curing. For example, in discussing "Free-Radical Photoinitiators and Initiation Mechanism" (Chapter 3 ), Dr. Koleske relates the story of how slow rates of acrylate polymerization for cementing bomber turrets during World War II was an impediment to commercial development. In "Free Radical Initiated Polymerization Systems" Chapter 5 ), Bill Burlant's saga of the 1950's in demonstrating the instantaneous cure of electron beam cured systems to Henry Ford and his senior staff is relayed. These vignettes ought to be read by the non-chemists in corporate managements to illustrate the arduous task and time-span of development for innovative technologies such as radiation curing.
Throughout Radiation Curing of Coatings there is an excellent balance between statements of fundamentals, as in the derivation of energy from light sources as found in "Radiation Curing" (Chapter 1 ) and the practical aspects involved in implementing this technology. Free radical and cationic initiation and chemistry are well covered (Chapters 3, 4, 5 and 6 ) as well as a summary of currently available equipment (Chapter 2 ). Dual cure systems are also dealt with including UV powdered coatings (Chapter 8 ). The diversity of options in "Dual-Cure Mechanisms" (Chapter 9) represents an under-exploited area of technology. The formulator will find the specific chapter dealing with additives (Chapter 11) to be most useful in that this is an area not often treated. To the chagrin of some smaller raw material suppliers, these various chapters dealing with materials include reference to specific grades made by specific major materials suppliers.
One market use, "Adhesives" (Chapter 10), is given some dedicated attention and includes a section on release coatings. However, many other markets for radiation curable coatings, including inks, are grouped together in "End Uses" (Chapter 13) in summary fashion. In keeping with the format of this book in general, some historical perspective is given to some of these market areas. "Safety and Health Considerations" (Chapter 12) is also only touched upon with reference being made to consult the RadTech web site. Finally, the "Glossary of Terms" developed by the RadTech UV Measurements Focus Group is included at the end of the book.
In general, Radiation Curing of Coatings is a solid technical work well suited for those involved in or interested in becoming involved in the radiation curing of low molecular weight materials, like inks, coatings and adhesives. It goes into considerably more depth, especially in chemistry, than RadTech's UV/EB Curing Primer( 1991 ) and is more current. Those in academia might consider this book to be a useful resource around which to build a coherent course on radiation curing in that there is still lacking a unifying text in this area.
ASTM Standards Rela