Investigations On The Adhesion Of Eb Cured Coatings On Metal Substrates

INTRODUCTION

Metals have a particular position in the field of electron beam curing of
coatings. At a first metals would be expected to be very suitable
substrates for EB example, many industrial metal products
possess flat surfaces, which is an-obvious advantage considering electron
beam curing. However, in practice the number of applications on steel,
aluminum or other metals is low, whereas a substantial market has been
generated for other substrates such as wood, paper and plastics. Our research
organization was interested in the question what arguments and reasons are
mentioned for the relatively slow introduction of applications on metals.
Therefore we carried out a detailed literature study on this subject (1].
At first a brief historical overview will be given. In the early days of EBC
(the fifties) some research work was already directed to metal applications.
For instance, the Ford Motor Company, had activities in this field, although
its first commercial EB-cured products was a spray-coated thermoplastic
dashboard. Besides, Ford sponsored an aluminum coating line at Wolverine
(late 60's). As the adhesion of the coatings on the metal substrates appeared
to be -inferior, these early attempts to develop' applications on metals did
not give rise to the construction of more production lines. On the contrary,
the qualification 'inferior adhesion' had settled for good and during more
than a decade everyone in this business quoted each other that *EBC on metal
substrates is handicapped by insufficient adhesion*. Only in the eighties new
hope and expectations rose, because Japanese companies were able to develop
EB coated products on metal parts. In' the USA and, Europe there is still a
more reserved attitude.

In our literature study, directed to.the backgrounds of electron curing
on metals, we examined the aspect of adhesion as well as the entire field,
including technical, chemical, physical, economic and psychological aspects
and arguments, which have played a role up to now. It was concluded that
electron-beam curing for metal parts isa realistic option 1].