Page 69 - Print 21 July-August 2019

Offset
one with food safe product, and is probably capable of printing on a wider range of substrates.”
The technology has a number
of disadvantages which may put printers off, such as higher prices of inks and consumables, and greater energy consumption. According
to Mollee, however, there are also plenty of upsides to consider.
“The key benefits are fewer emissions of volatile organic compounds; the fact that inks can dry on plastic and other non-porous substrates; and then they don’t have to absorb into the stock or dry fast,” he says. “Additionally, ink dots are left sitting on the substrate, reducing contamination and delivering more vibrant colour and detail; and higher gloss levels as well as superior rub resistance are possible.”
Mulligan adds that compositions of UV inks and washes are “vastly different” to their conventional equivalents, and thus need a system engineered for compatibility – but says that shouldn’t put people off.
“Perhaps the initial consumable cost is a little higher; however, this would be more than compensated with the productivity and quality gains, and reductions in waste,” he says.
Probably the most important consideration when weighing up UV is the press that you run it on. Richard Timson, managing director of press manufacturer Heidelberg Australia, says any press can be prepared for UV.
“Every packaging press would probably have UV on it, and in commercial, it depends on the application. The majority of commercial printing companies are not using UV at all,” he says. “Most packaging printers generally just print UV all the time, because the runs are longer and the end users require UV.”
Timson believes commercial offset printers don’t really need UV, unless they want embellishments.
“Standard commercial printing nowadays will produce a job with less setup, less complexity and less costs using conventional inks. Most
“It seems like a logical progression for many, especially given the new low energy solutions being offered by press manufacturers.” – Mitch Mulligan
UV requires a different skill set as well. It’s a bit of a different game. Some people would like to run a combination of both, but that’s tricky – normally you’d queue up your press for a batch of UV work, run that for a while, then switch back to UV. It requires a well managed process and still takes time,” he says.
Timson estimates that adding
UV to an existing press could cost between $300,000 and $500,000, with basic equipment needed including radiation shielding for the print unit, as well as UV-compatible inkers, blankets, and impression cylinder washup devices.
“Then there are inks, which are generally around twice the price of conventional inks, as well as
different power costs, because with different UV you have different levels of drying – so you need more energy to cure the ink, depending on the lamps and their power.
“You also have low energy UV, which previously had some popularity in the marketplace but is restricted
to non-food products because it’s not certified. Low-energy ink is also about four times the price of conventional ink, so you have a high cost for that
as well,” he says, pointing out that
the recent Chinese crisis, which saw chemical plants across the country temporarily shut down following an explosion, has hit supply by making it difficult to get photoinitiators.
Gunn, however, has seen sales of Komori H-UV and LED UV presses swing upwards in the last 10 years
as run lengths shorten, he says, “Komori’s sales proportion of LED and H-UV to commercial printers is approximately fifty per cent in Japan and ninety-five per cent in Australia.” Similarly the proportion of RMGT (formerly Ryobi) presses with LED UV sold into ANZ is more thahn 50 per cent, with the company claiming LED UV uses 80 per cent less power than the mercury vapour lamps.
Whether you are a trade printer looking to get as much work through as possible in the shortest amount of time, or a packaging printer wanting to offer food-safe printing, it might be a good idea to look at UV – because it is here to stay. 21
Opposite page:
UV offset: growing in popularity
Above:
Low energy: Heidelberg DryStar LE UV
Stepping up to the plates
A conventional press is nothing without plates to print with, and according to Rob Mollee, there are a couple of plate options for people using UV.
“Most of the legacy plate technologies can run UV when post-baked. Manufacturers have also brought out plates with increased robustness where you don’t need to post-bake: for Kodak that’s the Trillian SP and the Electra Max for UV print applications, as well as the processless Sonora X.
“Generally speaking, the UV capabilities are around the robustness of the plate emulsion, which must be able to resist the solvent washes and chemicals associated with UV. For a print application, we can use the UV compatible plate for any general work – it’s just more robust and will hold up better under UV conditions,” he says.
Mollee adds that plate volumes in the UV segment are growing for Kodak by about 10 to 20 per cent year on year, and says that no special chemistry is needed for UV plates.
“In a nutshell, working with UV compatible plates is no different to working with
plates for the standard offset market. They perform and handle the same in every way. It’s the same chemical and processing line-up across our portfolio,” he says.
Fellow platemaker Fujifilm’s range of UV- compatible plates includes the Superia LH- PLE and LH-PJE “lo-chem” systems, which
it describes as “high definition, positive- working thermal CTP plates for medium-run commercial print applications”.
“Both plates can also be used with UV inks, either unbaked or baked, and Superia LH-PJE in particular can be used for ultra high quality 10μm FM screening applications,” says Fujifilm.
The manufacturer also has its own process-free offering, the Superia ZD, which it says performs well on UV presses.
“Physical robustness is not the only strength of Superia ZD – it also has excellent solvent resistance so can be used with conventional and new generation UV inks,” the company says.
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