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INTRODUCTION
In the process of UV-curing, the characteristics of the light source have long
been a neglected factor. Adaptations of the formulation' (in particular, the
photoinitiator) have been the.action of choice whenever cure problems were
apparent, whereas the light source has remained relatively unaffected.
In recent years, pigmented UV-fromulations are drawing increasing attention.
Again, most of the research efforts or solving cure probleme with these
systems have been focused on of new photoinitiators that are
more sensitive to those wavelengths that are not or only partly absorbed by,
Nevertheless, UV equipment suppliers have now started to realize
that a number of cure problems with pigmented systems can also be solved by
using light sources with adapted emission characteristics. It thus has become
clear that UV-materials containing (rutile) 2 can be conveniently cured
with mercury lamps containing specific metal halide doping, which results in
an increase of high-wavelength emissions.
Although there are some reports dealing with this subject [1-5], not much has
been published about the sensitivity of UV—resins (i.e., photoinitiators)
towards different wavelengths. In this paper we will describe a study of the
dependence of the real-time infrared spectroscopic data on the wavelength used
for curing. This is realized by performing these experiments while using
optical interference, filters with narrow transmission bands.
The aim of this study was to gain more insight into the spectral efficiency
of the used light 'source' with respect to the photoinitiator used in the
develop lamps extremely suited for a specific class of photoinitiators, and,
on the other hand, would enable the photoinitiator suppliers to develop
initiators for efficient combinations with certain lamp types.
