Zdrojový dokument:Scientific papers of the University of Pardubice. Series A, Faculty of Chemical Technology. 19/2013
ISSN:1211-5541
Abstrakt:
Nowadays, UV curable systems (inks, varnishes) are frequently used in printing
industry. Their unquestionable advantages are the absence of volatile organic
compounds, good chemical resistance and short curing times (fractions of
second). A disadvantage of a UV-cured system is the possibility of migration of
unreacted photoinitiators, monomers and other substances from the cured
polymeric film. This parameter is of high importance in food packaging industry.
In most cases, migration is an unwanted effect during which the unreacted
photoinitiator or binder can be released from the package, contaminate and affect
the food. In some cases, slow migration of antioxidants from packages to food is
used intentionally. In this case, the antioxidants act positively on the food quality.
This paper is aimed at research of curing and migration of substances from a
cationically polymerizable system containing iron-arene photoinitiator Irgacure
261 and epoxidic binder Celloxide 2021P. The curing of systems was monitored
at different concentrations of photoinitiator via infrared spectroscopy. By UV/VIS spectroscopy, migration of photoinitiators was monitored under different curing
conditions and times of extraction. The results show that the greatest effect on the
extracted amount of photoinitiator was exhibited by the concentration of the
photoinitiator in the curing systems. With increasing curing time, the amount of
extracted photoinitiator decreased, but this decrease was not significant. The
UV/VIS spectroscopy data analysis is generally suitable for the determination of
migration of substances from simple systems (two or three components), but for
more complex systems is not appropriate. With larger number of components
(commercial inks and varnishes), there will be overlap between the absorption
spectra of individual components, and thus it will be impossible to determine their
concentration in the extract.