How to accomplish late stage customization with varnished folding cartons and UV LED inkjet printing
- Folding cartons coated with dispersion varnish formerly posed major challenges in regard to late stage customization, primarily relating to the adhesion, scratch resistance and print quality of UV LED ink.
- Already validated in practice, a development project has paved the way for brilliant UV LED inkjet printing in combination with a protective coating of glossy varnish.
Late stage customization, individualization and personalization, even with batch sizes of one, rank among the key concepts that are shaping the future of packaging. Practically every producer of consumer goods is already formulating plans, taking the first steps towards implementation, or applying the relevant practices.
Measured by quantity – paper, paperboard and cardboard continue to account for the largest proportion of packaging materials consumed in Germany. This situation is expected to change very little in the years ahead, in view of the growing global significance of paper as a renewable raw material. Given the increasing demand for customized packaging as well, the interest in digital printing systems for industrial purposes is also escalating.
Users are calling for digital printing and production systems that can be integrated almost imperceptibly into existing, finely tuned manufacturing processes while substantially, or even completely, closing the gap between efficiency and a batch size of one. Attempts to satisfy these demands, however, remain beset by limitations imposed by varnished folding cartons.
Most of the dispersion varnishes available on the market have two shortcomings when printed by inkjet with UV LED ink, namely
- a lack of adhesion and scratch resistance, and
- depending on the properties of the varnish, inadequate print quality.
In the absence of viable alternatives, industry has thus far reluctantly accepted these limitations and adopted selective workarounds – unvarnished knockout areas or additional investments in physical pretreatments exploiting corona or plasma technology.
“But none of these solutions genuinely satisfies the needs of discerning brand manufacturers,” says an ink expert of Tritron. This is because they fly in the face of the benefits promised by digital printing, which are:
- variable content,
- cost savings, and
- just-in-time output.
Blocking out the varnish is currently the preferred solution, provided that the unvarnished area is not too large. “It’s certainly not a problem if only a 2D code is to be printed,” the expert explains. “If, on the other hand, an entire side of a pack is to be individualized, which is one of the desired outcomes of late stage customization, the result would be visually unappealing because of the lack of gloss and brightness. This would adversely affect the advertising impact of the packaging at the point of sale.” On top of that, the varnish has a protective function as well. He points out that some packs would emerge from long journeys with a travel-worn appearance before even taking their place on the shelf.
Corona or plasma systems, in turn, apart from the additional investment, have their own drawbacks relating to flexibility, process reliability and efficiency. Setting up a plasma system can lead to the production of folding cartons that simply have to be discarded for quality reasons. In such cases, the process costs are considerable as expensive printing machines and their operators have forced downtimes.
Some time ago, with a view to eliminating the outlined shortcomings and fully exploiting the benefits offered by inkjet printing, Atlantic Zeiser and Tritron joined forces with ACTEGA, a company specializing in overprint varnishes, to launch a development project. The goal was to harmonize the ink and offset varnish formulations in order to completely remove the limitations of late stage customization endured by print shops and brand manufacturers alike, and at the same time to entirely omit surface pretreatment of the folding cartons. The protective varnish applied over the offset printing ink also serves as a primer for the downline UV LED inkjet printing process. Having undergone field testing, the joint solution is now ready for commercialization.
Among those who have endorsed the outcome is the ink specialist, who says, “The practical results are compelling.” The brilliance of the new inkjet varnish corresponds to that of conventional dispersion varnishes, and it performs equally well when being applied. It produces an unbroken protective surface on the carton that feels no different from the finish produced by other varnishes. The high-resolution print image achieved when the UV LED-curable ink developed by Tritron is applied to this inkjet varnish complies with the barcode grading A and offers excellent adhesion as measured by the TESA test. The UV LED ink is highly resistant to abrasion and very durable, and retains its distinctive attribute – a slightly raised print finish that creates an especially high-class and sophisticated impression.
Two prominent pharmaceutical companies are already utilizing this solution, pioneered by Atlantic Zeiser and ACTEGA, and a cosmetics manufacturer will be using the varnish in its production operation from the start of 2020. “Together with our partners, we have every confidence in the genuine value-added that we are offering,” explains Thomas Koop, Product Manager Paper-based Packaging at ACTEGA. “The new solution not only epitomizes quality and design freedom, but also enhances efficiency and underpins a reliable production environment.”
Atlantic Zeiser and Tritron likewise point to the opportunities that are emerging. “In conjunction with ACTEGA, we have removed the final hurdle that often stood in the way of comprehensive late stage customization,” remarks the ink expert. “An economically very sound proposition is now available to both brand manufacturers and printers. It delivers superior monochrome and four-color print quality – at speeds of up to 60 meters a minute. This solution transforms personalized packaging into a brilliant idea, in the true sense of the word.”