Price: 10.00
Introduction
Radiation curable products are widely used.
For some of these applications (f.i. overprinting varnish) the main requirements, for the
final coating are to be tackfree, hard and solvent resistant.
Recently the variety of applications where radiation curing is used, has strongly increased.
Coatings with extremely high performance and ultra fast curable varnishes require a better
knowledge of the properties of the coating.
Radiation curing is sometimes described as a technology where the final properties are
obtained in a very short time. It has however been observed that some properties of a
coating measured directly after the UV curing are not exactly the same as the properties
measured after a longer time. For example adhesion and hardness can increase in time.
Similar results were discussed in recent publications (1,2,3).
So contrary to the more conventional way of thinking which suggests that the end
properties of a coating which has been cured with UV or EB via a radical polymerisation
mechanism are immediately obtained, it will be shown that some changes in the properties
can occur.
In order to analyze this phenomena, several UV and EB formulations were prepared, cured
and aged. Different techniques were used to measure the evolution of some characteristics.
The influence of the initial energy to which the coating was exposed is also studied.
This study has the aim to measure the modification during ageing, but not to explain the
reason of such an evolution of properties.
