Printing technology has gone through a big change over the years. Printing markets have needed to adapt accordingly. This has also meant that clients’ demands have changed.
In recent years, the business area for original and customized items using UV inkjet printing is expanding for low-volume, high-mix on-demand production. The UV inkjet printer does not require a print-plate, thus the time of delivery and cost is reduced.
The new feature of UV inkjet printing enables to only print “what you need” and “when you need,” which provides an economic advantage in terms of stocking up to the final product. The optimal solution alternative to screen printing for low-volume, high-mix production is the UV inkjet printing and this trend will expand rapidly.
Traditionally, with UV-curable inkjet ink technology there has always been a trade-off between flexibility and durability. As the technology continues to develop we see more and more special inks offered, moving inkjet printing further and further away from the “one size fits all” approach to ink design.
Durability with Flexibility
Rigid board printing with UV-curable inks has been well served by inks that upon curing form hard, durable but inflexible prints. In order to be durable, these polymers cannot at the same time be flexible. For flexible substrates, the polymers must stretch to avoid cracking and flaking as the substrate bends.
Many ink and printer manufacturers provide a compromise ink that is useful for a variety of applications, but is neither as flexible nor as durable as it could be. This describes most general-purpose inks sold for use in flatbed, roll-to-roll and combo UV-curing printers. To avoid scuffing in many applications, a protective coating is often recommended.
When it is turned on, the printer delivers an additional top layer of ink from the light cyan ink supply, which contains a much more durable polymer than the other inks in the printer. Since the press is designed to produce indoor signage and displays that can be folded, flexible inks must be used to produce the six-color printed graphics.
The light cyan ink, if printed as a continuous film, would normally crack when folded. Instead it is printed as a set of closely spaced spots that do not touch one another. This allows it to be folded or flexed without cracking while still providing a high level of scuff resistance, avoiding the need for a protective coating in most applications.
High Volume Corrugated Package Printing
UV inkjet inks are promoted to “print on everything.” We all know that you can print on any substrate; the question becomes how does the print look? Does the ink stick? To accomplish this general-purpose performance, allowances must be made for plastics, paper, metal, etc., in the ink design.
The ingredients required for production of this high-performance ink are expensive, making the cost and thus the price high when competing with screen-printing where the ink costs are very low. This makes the run length breakeven point much more favorable in considering the press as an alternative to screen printing.
Thinner High-Load Inks
Another modification to ink design is being developed by Agfa. Its “Thin Ink” dispersion technology—available in several of Agfa’s new-generation UV-curing printers—allows them to use more pigment in its ink while at the same time, using less ink per image. High-load finely-ground pigments and a special dispersant—using technology borrowed from Agfa’s photo film manufacturing expertise—provide better image quality but requires less ink per square meter, according to the company.
This saves on ink consumption while also allowing faster, more even curing because of the thinner layer of ink to be cured.
Along with inks designed for LED-based UV-curing printers, there is an ever-increasing array of improved and specialty UV inks. They are designed to perform better in specific printers for specific applications, making UV inkjet a stronger and stronger competitor to analog printing. It’s safe to expect even more improvements coming soon.