UV Inks & Coatings — Coldset Printers Shine With UV
Advancements in ultraviolet (UV) curing technology—the process of transforming a liquid into a solid by using UV light—are responsible for some of the recent changes in the printing industry.
As an energy-efficient and green technology, printers everywhere have rapidly adopted UV energy curing inks and coatings to print on a variety of substrates, including metal, wood, fabric, plastics and a range of paper grades.
In the web printing arena, UV curing is now one option for the production of high-quality printing, at high speeds. This effectively closes the gaps that previously existed between coldset and heatset printing, in terms of sheetfed versus web speeds, and low productivity versus high-volume production.
UV ink technology has been around for more than 20 years, but until now it has not been an alternative production method for coldset printers. However, newly developed, more sophisticated UV-curable ink technologies are changing the landscape of the traditional coldset web printing operation.
UV-curable inks and varnishes typically consist of four main components: monomers, oligomers, pigments and photoinitiators. The photoinitiators are the catalysts that react to UV light of a certain wavelength, triggering a chain reaction that takes low molecular weight material (monomers and oligomers) and makes larger, high molecular weight polymers. These polymers then become so large by means of crosslinking that they form a continuous solid, or dry film.
Staying Above Surface
The drying of a conventional coldset ink film occurs when the ink vehicle (solvent, oil) is absorbed into the substrate, leaving behind the solids (pigments and resins) to form a film on the substrate surface. In energy curing, on the other hand, virtually all of the components in the ink or coating remain on the surface of the substrate.
Where does the true difference between UV and conventional ink lie? The difference is in the chemistry of the materials in the inks, and in the pressroom equipment needed to initiate the curing process. The materials, when formulated correctly, have made some newer energy curable ink formulas more user-friendly than ever before, making energy curable inks more common today and anticipated to be a growing segment in the years to come.
Knoxville, TN-based Alliance Press is one web offset printing operation that is exploring new print quality and performance potentials with UV coldset web printing.
The initial testing facility for a new ink designed specifically to enable UV coldset web printing, Alliance Press is running the new ink for a variety of full-web, coldset applications. The results: colors are vivid, blacks are deep, and marking and offsetting are no longer issues.
"We have been extremely pleased with the print quality and the additional product options it provides for us," says Matt Edwards, president of Alliance Press. "We are testing the UV process on commercial accounts every week, and the feedback we are receiving is highly positive. Customers are expressing great excitement that we can print on coated stocks, allowing them various opportunities for upgrading their publications."
Edwards sees the UV coldset web printing process as having the potential to fuel overall sales growth at Alliance Press by 35 percent to 50 percent in the coming year.
Is Alliance Press alone in its exploration of UV coldset web printing? Most likely, not for long.
No longer are UV installations showcasing strictly the traditional narrow- and half-web press environments. The ever-present need to maximize pressroom capacity, increasing environmental concerns and the desire to achieve cost savings are all factors contributing to the use of UV technologies in new applications. UV's comparatively small footprint on a shop floor is an additional selling point, and more and more printing operations are buying into the process.
Recently, Flint Ink developed a product that is creating a new area of opportunity for commercial coldset printers. Flint's Arrowlith UV ink technology takes the time tested process of UV curing and delivers it to coldset web printers. The new UV ink system is said to give coldset web printers the ability to print on stocks previously incompatible with coldset web technology, such as supercalendered stock and coated papers, broadening their existing capabilities and increasing pressroom productivity.
The new UV coldset ink system also enhances the quality of traditional coldset printing applications by creating images with sharper colors and higher gloss. Commercial printers gain the high-end, lustrous look of heatset inks, with the production and environmental benefits of UV inks. Arrowlith UV inks contain sufficient amounts of soy to qualify for the Soy Seal of Approval, and are also 100 percent free of volatile organic compounds (VOCs).
Coldset printers want to get into diverse and expanding business markets—markets which were previously closed to them due to technological limitations related to coldset printing. A publication printer, for example, traditionally has the cover printed separately, off-site in a heatset plant. UV coldset technology gives them an entry into a commercial printing market segment.
Another example is newspaper printers that often outsource full-color insert work to other printers. UV curing technology allows these newspaper plants to keep the jobs in-house, without dedicating an entire press to insert production.
Installing UV curing systems is considerably less expensive than heatset systems, which require pollutant-controlling equipment. Additionally, UV inks do not dry in the fountains, so they can remain overnight if necessary. This results in less spoilage in the ink fountains. And while UV inks are slightly more costly than conventional ones, less ink is used and the results are better.
Scott Stewart, president of Nebraska Printing Center in Lincoln, is another commercial web printer printing on newsprint and coated stock that is benefiting from new UV coldset technology.
"We represent to our customers that the UV coldset process is an excellent first cousin to heatset," notes Stewart. "Every customer we've sold on UV coldset has stayed on UV coldset. And we have not even started to tap the potential market."
Stewart's business caters to a diverse customer base, with web press customers including grocery and lumber retailers; real estate; automotive; specialty publications; religious, veteran and fraternal publications; and government and healthcare publications. The results of printing with the UV coldset ink system have been so well received that the company is currently running UV coldset on two separate press lines.
"We were advised by Flint to plan on a learning curve of three to four months," says Stewart. "That prediction was accurate, although the learning curve has been shorter on our newest press."
With a relatively small capital investment in UV systems, a coldset web printer can increase the opportunities from printing only on newsprint to having the ability to print on a wide variety of substrates.
"We've invested in the new technologies to be able to provide more services to our current and new customers," adds Stewart. "We see UV coldset as the future of web printing. UV will improve the quality of coldset printing just as the launch of USA Today caused daily newspapers in the United States to improve color reproduction and design."