Original scientific paper
Improving the security of conventional and UV luminescent flexographic prints by modification of the printing inks using nanoparticles
Tamara Tomašegović
orcid.org/0000-0002-9865-0604
; University of Zagreb Faculty of graphic arts
Sanja Mahović Poljaček
orcid.org/0000-0001-8242-7427
; University of Zagreb Faculty of graphic arts
Ivona Jurišić
Abstract
The security and protection of printed products against counterfeiting have become more advanced
and increasingly used in the field of graphics technology. In this research, conventional process black
(PB) and UV luminescent (UVL) inks used in flexography, modified by nanoscale silicon dioxide
(SiO2), anatase and rutile titanium dioxide (TiO2), and zinc oxide (ZnO) at different concentrations
were used. The purpose of adding nanoparticles to these inks was to protect PB and observed UVL
inks from counterfeiting without significantly affecting the optical appearance and colourimetric
properties of the printed motives.
The results have shown that nanoparticles did not significantly affect the spectral reflectance of
UVL inks observed under UV irradiation or the visual effect of UV luminescence. In addition,
the nanoparticles had a negligible effect on the optical and colourimetric properties of PB inks, as
evidenced by a slight increase in colour lightness after the addition of nanoparticles. Indirect detection
of nanoparticles through their interaction with PB and UVL inks was possible through FTIR-ATR
spectroscopy, which showed changes in the spectra of PB and UVL inks with nanoparticles compared
to nanoparticle-free inks in the fingerprint region. This research opened the possibility of expanding
the use of nanoparticles of different types and concentrations for process, spot, luminescent and other
special and conventional inks in the field of graphic technology.
Keywords
flexography, security printing, luminescence, nanoparticles, colourimetry
Hrčak ID:
300906
URI
Publication date:
28.4.2023.
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