LED curing is one of the most intriguing areas in energy curing. In 2008, LED curable technologies debuted at drupa, with plenty of press and ink manufacturers showcasing the technology. LED curable technologies have made inroads in the inkjet field, with Sun Chemical and INX Digital among the most notable ink companies working in the field.
Tom Molamphy, vice president of sales and marketing for Phoseon Technology, said that drupa 2008 was the first major event where people started to take notice of UV LED technology, most notably in inkjet applications, where the technology has had its strongest success.
“There is a lot of enthusiasm, particularly in the digital world,” Mr. Molamphy said. “Our company has grown significantly in the past two years, even despite the downturn, and we expect that to continue over the next several years. Digital has become the strongest market. There is a lot of innovation in inkjet in general, and the advantages of UV LED play well to inkjet’s needs. Still, it will take time for LED to become the dominant player in inkjet.”
LED technology has been available for a while, but the ability of ink manufacturers to develop LED-compatible inks has been an important driver.
“The ink companies are primarily the drivers, and ink formulation is critical,” Mr. Molamphy said. “The early LED inks needed to be tweaked or completely reformulated to optimize for LED curing. The biggest issue today is the business case, but the interest in formulating inks that are UV LED specific is now there from the customers.”
Mr. Molamphy noted that there are a lot of advantages to UV LED. “UV LED tends to have stable outputs over long time periods, and 20,000 to 30,000 hours of useful life is certainly possible,” he said. “Electricity usage is lower, and is particularly noticeable for flexo and sheetfed applications where the UV systems are larger and use more power. A printer should expect approximately 50 percent savings in terms of power for each unit. It releases no ozone, as it operates in the UV-A spectrum. The units are physically smaller, and as solid-state devices, are easier to integrate and control as well as to provide maintenance. We expect that our units should outlast the useful life of many of the digital inkjet machines where they are presently installed. In addition, mercury usage in lamps is becoming an issue in Europe.
Photo courtesy of Phoseon Technology.
Mr. Shouldice said that Sun Chemical has UV inks designed specifically for LED curing units in a variety of market industries, but the majority of LED lamps used today are in inkjet applications.
“SunJet, the inkjet ink division of Sun Chemical, is a leader in the development of UV curing inks and has supported the industry developments in LED UV lamp technology for several years,” Mr. Shouldice said. “It was one of the first ink companies to recognize the potential benefits to customers of inks which have the ability to part cure or ‘pin’ with UV LED lamp exposure in scanning head systems.
“As lamp technology has advanced and higher power lamps have been demonstrated, SunJet has managed to produce graphics inks which fully cure with LED UV exposure,” Mr. Shouldice added. “SunJet CRYSTAL UFE – LED inks are an ink chemistry specifically designed for curing under exposure to UV light from LED sources. SunJet CRYSTAL UFE – LED inks are designed for use in single pass and scanning wide format applications which raise the achievable line speed by more than three times. Adhesion to PVC, hard plastics and metals with these inks has been achieved.
“SunJet ink chemists have been able to increase cure speed significantly and apply the speed increases to other SunJet ink families – an important requirement for our customers if LED curing is to become a reality,” Mr. Shouldice added. “Increased line speed on this scale really widens the scope of LED curing as a method of drying inkjet films. We see application in coding and marking, digital label production, wide format graphics and in variable data printing on plastic smart cards.”
At Print 09, INX Digital showcased a short-run narrow web UV LED press, which features single-pass output at through-cure speeds of up to 80 feet per minute. Recently, INX Digital exhibited its LED-INX, a UV-curable pigmented inkjet ink that is in the development phase.
On the conventional printing ink side, leading ink manufacturers see the potential for UV LED’s growth, and are preparing for UV LED to reach the market. Jonathan Graunke, vice president – energy curable technologies, for INX International Ink Co., said that the UV LED market has been reasonably good for most of the year. “It appears that over time, more people are learning about it and willing to try something new,” he added.
“It seems that all existing printing processes could use UV LED curing,” Mr. Molamphy noted. “We see some really good specialty screen applications in areas such as rotary screen for bottles and plastic. Flexo is a good possibility due to the narrow web presses, although flexo printers do tend to use a lot of different ink sets. Sheetfed is also a good opportunity, although there is work still to be done on the higher print speeds and wider sheet sizes as well as requirements for greater distances between the UV-LED source itself and the print media.”
The economy remains a drawback to UV LED’s growth, though.
“LED was one of the novelties in the last two years,” said Peter Hilpert, BU head, labels and sheetfed/UV EMEA at Siegwerk. “Everybody is interested to see how it works and to benefit from the advantages of this technology. But we haven’t seen a real trend to new equipment, certainly also based on the weak economy and the restrictions on capital expenditure in this period. We at Siegwerk believe in this technology and we further develop the next generation of LED inks together with lamp and press suppliers.”
“The interest is there, but there are also delays in developing LED technologies, particularly in a sluggish economy. Companies just don’t have the capital to invest in press and curing equipment development,” John Copeland, president and COO of Toyo Ink America, LLC, said.
Overall, there does appear to be strong opportunities outside of digital printing for UV LED.
“LED curing technology is looking more feasible every day, and there is a market out there waiting for it,” Damon Geer, vice president, Zeller+Gmelin Corporation, noted. “It’s still a few years away from being a practical reality in the pressroom, but progress has been made and at some point next year we will be seeing these units on selective printing equipment.”
“There is some interest in LED curing, especially in inkjet,” Dr. Don Duncan, director of R&D at Wikoff Color, said. “LEDs also are beginning to make a small penetration into UV flexo and UV litho. At the moment, LEDs are still fairly expensive and much lower in curing power output than lamps. Also, the inks must be reformulated to use somewhat higher-cost raw materials. Still, the mercury issue in the standard UV bulbs may drive the technology toward LEDs over the next few years.”
Overall, Mr. Molamphy said that the improvement in LED-curable technology has been impressive.
“We are so far past where we were four years ago,” Mr. Molamphy said. “In terms of faster speeds and improved quality, the improvement in LED equipment is staggering, and it is getting better fast.”