The costs are going down primarily because UV curing has become more energy efficient. Advances have been made in cutting the energy consumption of existing UV curing technologies. New low-energy technologies – in particular LED-based systems – are also transforming the future for UV.
Ink producers are making a major contribution through newly developed highly reactive inks. The big challenge for ink makers will be to keep up a steady stream of innovations to help maintain energy efficiencies.
Reducing Energy Consumption
The trend to lower energy consumption in UV curing of printing inks has been gathering pace in the wake of efforts to make the process cleaner and safer by the introduction of equipment that filters out wavelengths lower than 290 nanometers (nm). This eliminates the creation of ozone during printing, which, without the use of an abatement system, can endanger the health of print workers.
Ozone-free curing adds to the health and safety advantages of a process that already provides the benefit of having inks and coatings with little or no volatile organic compounds (VOCs). As a result, UV printing has already had cost gains for printers complying with new European Union regulations tightening up controls on VOC emissions because, unlike printers using traditional solvent inks and coatings, UV printers have not had to invest in recapturing and incineration equipment to eliminate VOCs.
The shifting of the output of UV lamps to higher wavelengths has made them even more energy efficient with an energy consumption considerably lower than that needed to dry solvent or heatset inks or coatings.
In addition, highly reactive inks have been developed which help reduce even further the energy consumption of the lamps. Some lamps also have reflectors and power control units to help cut energy output.
Komori’s H-UV system, which was introduced to Europe with a demonstration at the 2012 drupa in Dusseldorf, Germany, utilizes a single UV lamp head to instantly cure highly sensitive UV inks. The curing system can achieve a 20% productivity increase when compared to conventional printing, helped by the requirement for 63% less energy than that used by infrared and warm air drying units.
Komori’s technology can provide instant curing in a four-color press without the need for any varnish or coating, thus avoiding the need for a printing unit or coater.
At a time of fast job turn-arounds, the H-UV lamps aid rapid printing by drying sheets so thoroughly that they can be delivered immediately back into the feeder for reverse-side printing.
In 2012, Heidelberg launched its DryStar low-energy UV lamp system for commercial, light packaging and specialty applications. The system utilizes UV reflectors, which reduce heat from the lamps, while materials in the lamps also eliminate the wavelengths below the ozone-creating 290 nm level.
The DryStar system allows for flexibility to control equipment costs. The printer also has the option of applying traditional UV inks rather than the more expensive highly reactive inks.
The VariDry HR UV system, launched by KBA also to coincide with drupa, offers variability so that the energy output can be adjusted to between 80 and 200 watts per square centimeter. It can used with conventional mercury lamps, which have a greater lifespan than iron doped lamps.
Low Energy Curing Inks
One result of the innovation in UV equipment, as well as in inks, is that overall costs are driven down to levels that make UV more economic for higher-volume printers. It is helping make UV curing attractive to conventional printers, who can achieve fast turnarounds by eliminating the need for infrared and warm air drying units and by reducing downtime.
“As commercial printers are pushed to offer shorter and shorter lead times, work-in-progress must be kept to a minimum,” explained Richard Wilson, Flint Group’s UV product management director.
“Low energy UV curing will allow the conventional commercial printer to manufacture to these new targets,” he added. “We see the web-to-print sector, in particular, being early adopters of this technology, because of the dramatic reduction in manufacturing time and the lower entry cost than traditional UV.”
Like most other leading ink makers, Flint Group has been developing new UV inks that enable printers to obtain even lower levels of energy consumption during the curing process.
Flint has just launched under the Ultraking XCURA label, a new range of low energy UV curing highly reactive inks and coatings for sheet and web offset applications. They can be printed on certain non-porous, as well as coated and uncoated, substrates.
“These inks are formulated using a selection of photoinitiators which absorb the higher end of the spectrum and are optimized for high speed curing,” said Rod Balmer, Flint Group’s director of global research and product development. “These inks are highly reactive, while the need for multiple UV lamps is not necessary, thus reducing operating costs for the printer.”
Flint Group has been working closely with press equipment and lamp manufacturers in the development of the ink range. The inks have successfully undergone beta trials with printers across Europe.
“We have worked hard to optimize XCURA’s performance across a wide range of applications to ensure it offers the ultimate in versatility to the user,” said Jim Buchanan, Flint Group’s business development director for UV sheetfed.
The company is also scheduled to introduce UV LED inks under the XCURA label for sheetfed applications early this year. “These will be appealing to the industry on a wider scale given the potential energy savings and process efficiency gains derived from the use of LED as an alternative curing method,” said Buchanan.
UV LED Inks
A growing number of ink producers are tackling the challenge of developing inks for the rapidly growing UV LED segment, whose inks require different formulations from those for conventional UV curing. These include Sun Chemical, Agfa and the German-based Ruco, Jaenecke + Schneemann and Marabu.
The main drivers behind the increasing sales of UV LED systems are their low energy costs and versatility. Printers using UV LED are reporting energy consumption as much as 70% lower than conventional UV systems. Another attraction of LED systems is their color brilliance stemming from higher pigment content.
UV LED lamps are alternatives to the mercury vapor lamps that have been around for more than 130 years. The mercury lamps now have an uncertain future in Europe not only because of new technologies, but also due to EU legislation restricting the industrial use of mercury for environmental and safety reasons.
LED lamps are more energy efficient than mercury since their discharge of light can be concentrated on the higher wavelength part of the spectrum. Mercury lamps can easily achieve irradiance levels of more than 10 watts per square centimeter, which is more than adequate for surface curing. LED lamps have tended to provide irradiance of less than half that level.
Recently, LED system producers have been boosting the energy generation capacity of their equipment. Integration Technology of the UK has, for example, introduced an LED system with a power output of 12W/cm2 at a wavelength of 395 nm.
The higher irradiance is making UV LED curing more versatile so that it can now be applied to a larger variety of substrates. Many of these substrates had been inappropriate for UV curing because the relatively intense heat of mercury lamps would be liable to wrinkle, shrink or even burn the substrates.
With the use of LED in screenprinting, UV curing can take place, for example, on bubble and shrink wrap, ultra-thin films, foils, laminates, a range of plastics and boards and glass.
The greater the variety of substrates and the more customized the use of UV LED curing, the greater the challenge for ink producers to match the application with the right ink. As a result, LED system providers tend to work closely with ink makers.
There are signs that UV LED is moving beyond niche into higher volume segments in some European countries, such as sheetfed printing, where the technology has the advantage of being able to provide high color strength.
In a recent study of the UV LED sector, Yole Developpement’ Lyons, France, predicted that, due to the low cost of ownership, the compactness of the equipment and its environmental friendliness, the global UV LED chip and package market would grow six-fold in 2012-2017, from $45 million to $270 million. This is equivalent to a compound annual growth rate of 43%, four times higher than that for traditional UV systems, which in 2012 accounted for close to 90% of the sector.
Because of the potential for UV LED systems to be miniaturized and even portable, entirely new markets could be opened up to UV curing. “(These) would increase the overall UV LED market size to nearly $300 million,” said Pars Mukish, LED technology and market analyst at Yole.
As a result, LED could within three years account for more than a third of the total world market for UV equipment, ancillaries and consumables. In Europe, with the potential for the creation of niche segments and the need for lower energy costs, the market share could be even higher.
European Editor Sean Milmo is an Essex, UK-based writer specializing in coverage of the chemical industry.