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 Related to Testing of Radiation-Cured Coatings is a compilation of 105 ASTM Test Methods, Practices and Guides related to the radiation curing area, including those developed for electron beam technology. These are well indexed by areas of interest in the front of the book as well as having the customary ASTM format of indexing at the end. This supplants RadTech's Radiation Curing Test Methods ( 1988 ) published under license from ASTM with its 62 Methods, Practices and Guides, many of which have since been up-dated and revised. The cross references and indexes in this new compilation adequately replace the explanatory text RadTech had developed for its 1988 book. Missing, however, are the conversion tables which can be found in any basic physics or chemistry handbook.

Of keen interest to the contemporary user is that this new compilation from ASTM is also available on CD-ROM. The CD has an auto-launch feature which brings up the compilation onto a computer screen immediately after inserting it into a CD drive. On the disk, there is both a "Table of Contents" of all of the "Standards and Related Materials Contained in this Volume" and a "Topical Contents" listing. Of significant benefit is the built-in search capability. Thus, one can do key word searches for ASTM documents pertaining to a specific area of interest. The print or CD versions are available at the same cost.

About the Author/Editor: A brief biographical sketch of Dr. Koleske is on the back outside cover of Radiation Curing of Coatings noting his long industrial career, mainly with Union Carbide, his numerous publications and patents. In RadTech International North America's formative days, Joe was often a participating lecturer on chemistry at seminars RadTech had then sponsored.

About ASTM International: Both Radiation Curing of Coatings and the ASTM Standards Related to Testing of Radiation-Cured Coatings have been published under the auspices of ASTM Committee D01 on Paint and Related Coatings, Materials, and Applications. This committee deals with many of the areas of interest to RadTech members, such as inks and coatings. RadTech members are invited to join ASTM and this committee. There are plenty of issues germane to the radiation curing industry that this committee deals with. For information on ASTM and D01 membership, visit the ASTM International web site at: www.astm.org or contact Tim Brooke, the ASTM Staff Manager for D01, at 610-832-9729 or tbrooke@astm.org.

Tony Berejka is a co-founder and Past-President of RadTech International North America. He is a member of ASTM D01 and D14 on Adhesives and has been a member of ASTM International for over 30 years.

Radiation curing technology can increase production, save money, improve working conditions, and decrease pollution. Manual 45, the only practical handbook of its kind, focuses on this growing technology and is specifically directed at those who are in the field of radiation curing of coatings, adhesives, inks, and sealants.

The manual's straightforward style makes it easily understood and allows readers to go directly from the book to their specific work area of radiation-curing technology. In general, the book relies on written explanations rather than numerous figures and tables. Because it impartially and objectively deals with these topics, the reader can decide which particular chemistry to pursue.

Industrial applications include: overprint varnishes, printing and graphic arts, automotive, plastics, electrical, electronic, optical, UV powders, and wood finishing.