PakMarkas, a packaging converter based near Vilnius in Lithuania, has retrofitted a UV LED curing system to a Comexi flexo press that already uses electron beam curing, allowing overprinting, cutting minimum run lengths and reducing the cost of the LED inks.
The company was started in 1994 by a young graduate, Virginijus Gumbaragis, now the company’s CEO, who saw an opportunity in a government decree obliging all food producers to package their food products. He began by selling packaging materials, packaging equipment and printed self-adhesive labels. Today PakMarkas has over 230 employees and is one of the largest tag and label printers in Lithuania. Roughly 30 percent of the company’s business comes from export, with over 400 active customers across Europe, mainly in Poland, Germany, the Scandinavian countries, Ukraine and Belarus.
The company has seven presses plus inline screen and digital printing, and added-value processes such as embossing, debossing, lamination, hot and cold stamping. It runs 24 hours a day, 5.5 days a week, producing on average 140 jobs a day, which rises to over 200 jobs per day at peak times. It takes roughly 5 working days to turn around a label job, or seven days for a shrink sleeve job.
In 2002 PakMarkas turned to GEW UV to install a UV system on an Arsoma press, which is still running today. This led to other retrofit projects, including adding 11 E2C mercury arc lampheads to the company’s Omet Varyflex 420 Press in 2014.
Around 10 years ago PakMarkas bought a Comexi 10-colour FW 2110 CI Flexo Press with electron beam curing. The company has now added LED UV curing technology to this press, which has enabled it to overprint opaque white ink on the front surface of their products. Previously, everything had to be reverse printed as all inks are cured together at the end of the machine by the electron beam system, which ruled out any food contact packaging.
Gumbaragis explains: “We moved over from arc to LED for several reasons. Firstly, low migration LED UV ink has less photoinitiators and is better suited to food contact packaging. Secondly, we work a lot with opaque white and LED UV is especially good for achieving a deep cure for this ink. And finally, LED was preferred for its lower power consumption.”
He adds: “We first looked at LED curing five years ago and at the time we did not think the technology was fully ready, but when we revisited it more recently and trialled it, the curing results were really very good. The energy levels are easily controlled and we can work within a very narrow band width. We have found that the combination of electron beam and LED UV curing is working very, very well for us.”
This has also changed the way the company approaches run lengths, as Tomas Deksnys, head of Prepress & Printing explains: “Most printers would consider 300 kilos of printed material to be a small order for the Comexi, but because we have the UV and EB installed on ours we can economically run jobs as small as 50 kilos.”
He adds: “Furthermore, having UV and EB curing on the Comexi enables us to reach very impressive production speeds of up to 300 metres per minute, with an 840mm width web. Our production capacity on the Comexi is huge but at the same time, thanks to the UV & EB installations, we can economically run a multitude of smaller jobs on that press. Because we are not using solvent-based inks there is no need to clean down after every job. UV & EB inks do not dry naturally, so they can simply be left in the machine for the next job.”
PakMarkas has also found the combination of the two curing systems helps to keep down the cost of the LED UV inks. Deksnys explains: “On the Comexi, the LED UV base white ink only needs to be pre-cured enough to be able to be overprinted. This means that we can purchase inks which are formulated with a much lower photoinitiator content and which therefore cost considerably less. Our ink manufacturing partners have been most helpful here and we have found the perfect formula together.”
He adds: “The beauty of our system is that the electron beam used at the end of the run completely cures all inks, and without any reliance on photoinitiators. Any remaining unreacted components in the LED UV ink are in any case fully cured and made safe before rewinding.”
Gumbaragis concludes: “Fulfilling a high volume of short-run orders very quickly is our major strength, and our UV curing systems make this possible on every machine.