SunJet, the inkjet ink division of Sun Chemical, announced at drupa the development of new and novel ink chemistry specifically designed for curing under exposure to UV light from LED sources. In laboratory tests, line speeds in single pass applications have exceeded 100 meters or 300 feet per minute.
SunJet has supported the industry developments in LED UV lamp technology for several years, and 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. What was announced at drupa is a further step change in performance and in application.
In the last two months, SunJet has produced a set of inks designed for use in single pass applications which raise the achievable line speed by more than three times.
In addition to this improvement, SunJet has discovered a route in formulation which allows the increased response to LED UV output to be applied to a full range of SunJet ink families. This means that ink sets such as SunJet’s flexible inks can be used with the new LED lamp technology if correctly integrated.
LED lamp technology is important because it can reduce the complexity of integrating UV curing lamps, can reduce the environmental and health and safety concerns in some applications and also allow use of UV curing technology on heat sensitive substrates.
“We have seen full cure of ink films, including surface cure, in 12 micron ink films when using 365nm and 395nm wavelength lamps,” said Hartley Selman, SunJet UV ink development specialist. “We can demonstrate full curing with energy doses of 30mJ/cm2 and below which allows the system to effectively run faster, which is what our customer base is demanding if LED curing is to become a reality. We have achieved adhesion to PVC, hard plastics and metals with these inks, so they are functional.”
“Our ink chemists have been able to increase cure speed significantly and apply the speed increases to other SunJet ink families,” said Peter Saunders, sales and marketing manager. “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.”