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UV curable liquid coating technology has been around for years. Primarily used in the lithographic and screen print industries, UV curable liquid coatings were used either to achieve a specific, finished look or to provide abrasion protection to printed images. For years, these industry paths have seldomly crossed, but that is no longer the case. The localization and personalization of print campaigns made possible by digital printing have changed things forever. Runs of 2,000 to 20,000 prints or more are no longer required to be competitive. The widespread use of digital printing has created a technology crossover like no other in the imaging industry. In addition, the methods and equipment used for printing and finishing also are transforming into smaller, faster, more user friendly and less expensive products. This metamorphosis has affected UV curable liquid coating technology.

The demand by digital printers for less expensive UV curable liquid coating technology has improved the design of coating equipment as well as liquid coating formulations. UV curable liquid coaters that previously measured 17-25 feet long to accommodate long UV curing paths have been shortened to as little as three feet long. These more compact liquid coaters still can achieve 95 percent of the coating smoothness of the longer coaters because of advances in equipment design and coating formulation.

Besides quicker curing times, today's liquid coatings have advanced to offer a variety of specialty finishes and applications. What was once an offering of a basic gloss, luster or matte finish has blossomed into a host of coating types that include specialty products like dry erase, anti-graffiti and even anti-slip finishes. Truly, a window of opportunity has been opened when it comes to UV curable liquid coating technology in terms of reduced cost and a wider variety of available products.

The reduced cost and advanced design of UV curable liquid coatings and coating equipment has enabled graphic manufacturers to be more creative in problem solving. For example, the print heads of UV flatbed printers are mounted onto a carriage that traverses back and forth over the substrate, laying down a swath of UV curable ink in each direction. Substrate panels are advanced continuously through the printer laying down swath after swath of ink. The ink is then cured by a set of UV lamps riding on the backside of, or set back from, the carriage. The print quality mode used, especially in older printers, will have a drastic effect on print quality due to the lay down time. If a printer is running in a fast production mode, sometimes the inks do not have enough time to flatten completely before being cured. This results in ink lay down patterns, commonly referred to as lawnmower marks, or the lawnmower effect.

This presents a problem for the printer. Do they run the printer in production mode since the output in this mode is likely what they based the purchase of the printer on? Or do they slow the printer down to provide a higher quality product to the end user, which in some cases can take them out of bid contention for the job? For some graphic houses, like PPI Imaging in Monroeville, PA, the question to save cost over quality is solved by adding UV curable liquid coating capabilities to their shops.

PPI Imaging owner, Wayne Palmer, owns an older UV flatbed printer and was considering upgrading his printer. "I have an older UV flatbed that didn't allow me to compete quality-wise with some of the newer print technologies," Palmer said. "I was facing an upgrade of my print technology to the tune of about $250,000."

After looking at UV curable liquid coatings, Palmer realized he could increase the quality of his prints by applying a liquid coatings to mask print head banding and improve color pop. Once he did some testing with output from his printer, the choice was certain. "I printed some sample prints about as bad as I could and sent them out to be coated and I was amazed by what came back," he said. After seeing how finishing his prints with UV curable coating could improve the quality, Palmer decided to add a large format UV curable liquid coater to his shop for a much smaller investment than upgrading his flatbed printer.

"That single investment, which was way less than a printer, now enables me to print in production mode for many of my print jobs and compete, bid wise, with the big boys due to the time and ink savings," Palmer explains. "It has allowed me to double my UV printing business in the past six months."

Weighing in at a hefty $85 billion, the worldwide paint and coatings industry is much larger than all of the graphics industries put together. The resources in the paint and coatings industry support the technology to develop almost any product imaginable. For example, there are now UV curable liquid coatings that can be thermo-formed, a product that did not exist a few years ago. In addition to thermo-formable liquid coatings, coating products available today include:

• Anti-slip coatings for floor graphics
• Dry erase coatings for whiteboard applications
• Translucent white coatings for flood coating backlit prints
• Flexible coatings for short-term fleet graphics
• Primer coats that provide an anchor point for printing onto low energy substrates such as glass, tiles and hard to print plastics such as polyolefin
• Photo coatings that can be sanded, re-coated, signed and embossed
• Flame retardant and antimicrobial

Comparing UV Curable Liquid Coatings to Other Finishing Technologies
One area where UV curable liquid coatings fall short when compared to aqueous coatings or traditional film laminates is in providing long term protection from color fade caused by UV light. Unlike aqueous coatings and laminate films that can be fortified with UV inhibitors that prevent UVA from getting to the ink, UV curable coatings use UV energy to cure. This makes it challenging to add UV inhibitors that extend the life of inks, which has a direct influence on curing and, hence, other properties of the coating itself.

The more inhibitors added, the less these coatings cure or the more the coatings have to be modified into hybrid coatings that cure. Also, hybrid coatings may no longer offer the VOC-free and eco-friendly attributes of the more popular Acrylate UV curable coatings typical in our industry, which are considered to be 100 percent solids.

In spite of this challenge, UV curable coatings and coating systems offer significant advantages over aqueous and film alternatives because of lower cost, process speed and process flexibility. While the initial cost of a UV curable system will be more expensive than an aqueous flood coater or a film laminator, the payback in all other areas is worth serious investigation.

Cost Comparison
Typical film laminate costs will range from $.20 to $.30 per square foot on the low end, to well over a dollar for specialty applications like floor or vehicle graphics. Aqueous liquid coatings, comprised largely of water (up to 70 percent), range from about $65 per gallon up to $160 per gallon for specialty applications (e.g., anti-graffiti). This translates into costs between $.04 and $.40 cents per square foot. The cost range of UV curable coatings is much less than either film laminate or aqueous coatings, even for the specialty applications ranging between $.01 per square foot to $.15 per square foot.

In addition to material costs, UV curable liquid coatings realize costs in waste reduction. Both aqueous and UV curable liquid coating technologies cut down on waste, but UV curable is often the preferred choice, with waste around two percent (compared to film laminates at over fifteen percent). Liquid coatings also have lower labor and electricity costs over film laminates and significantly reduced storage space costs.

Process Speed Comparison
Depending on the liquid coating equipment, some systems offer roll-to-roll features that coat a 300-foot roll of vinyl in less than six minutes and handle take up duties automatically. In addition, UV curable systems do not require immediate clean up after the job; the equipment can go days between clean ups, depending on the type of substrates and coatings they are running. Due to the high process speeds and more compact footprints of the majority of UV coating systems, the overall cost of ownership is much lower than any other form of lamination.

Process Flexibility
The number of ways in which today's coatings can be used to enhance or enable you to hit the ground running and hang onto a customer by creating custom finishing options is greater today than ever before. It includes creating custom textures, custom gloss levels and turning weather-prone products like Re-board™, usually thought of as a short term, throwaway product, into a much longer-lasting outdoor product, warrantable by the manufacturer if coated and sealed properly.

UV Curable Liquid Coating Technology in the Future
Given all of this technological advancement, where do we go from here? Several new projects in the UV coatings arena have more to do with expanding the applications window than with enhancing equipment performance. This is a good thing since finishing is no longer a bottleneck, at least not when we're talking about liquid coating versus film lamination. The new buzz is about coatings that enable the capabilities of other products. For example, new coatings enhance the fire retardant properties of certain products normally unable to meet this requirement on their own. Or, anti-microbial coatings that actively kill surface bacteria for applications such as digitally printed wall coverings and countertops. Other applications include surface primers that enable digitally printed menu boards to withstand exposure to alcohol and other chemicals that would normally cause inks to deteriorate rapidly.

UV curable technology, for printing or coating, is the future. Whoever does not embrace it is likely to get left in the dust. Understanding how to make UV curable liquid coating technology work for you is the key to unlocking an opportunity for greater profits and staying power. Graphics producers no longer can ignore the advancements of UV curable liquid finishing and expect to compete in an industry where technologies are geared toward enabling smaller businesses to compete and win.

Jim Tatum has more than 18 years of experience in the film and liquid lamination industry. Before joining Drytac as VP of the Liquid Finishing Division, he gained his knowledge and application experience while owning and operating Advanced Finishing Solutions (AFS). Prior to AFS, he was with Neschen for more 15 years. Tatum received his degree in Business Management from the University of Phoenix. jimtatum@drytac.com

This article appeared in the SGIA Journal, 2nd Quarter 2010 Issue and is reprinted with permission. Copyright 2010 Specialty Graphic Imaging Association (www.sgia.org). All Rights Reserved.