A deep dive into single-pass digital inkjet printing onto corrugated packaging.
By Mark Hanley
To combat this, some of the sheet systems vendors are offering a hybrid known as water-carrier UV inks. Such systems are very new to the market, so it remains to be seen how they will actually turn out. The theoretical advantage is that, with a water carrier, you get a flatter and better graphic image than with UV inks with 100-percent solids. A large part of its makeup is monomers – surrounding colorants – which cure transparently but in a lensed dome, causing color gamut, reflectance, and physical conversion problems. A water-based carrier allows you to get rid of a lot of those monomers and the associated problems, though of course now you have to dry water. Drying water is still a nuisance, requiring energy and space, and has potential adverse effects on the substrate. But the hope and belief is that these problems are much less severe in water-carrier UV systems than in purely aqueous systems.
Inkjet’s Different Formats: Roll or Sheet
Both sheet and roll systems are being offered, which illustrates the complexity of the corrugated market. Sheet systems are meant to be installed late in the manufacturing process at the box maker’s facility, usually to allow the latest-possible determination of print content in order to stay relevant. These systems allow sudden, very short runs to be produced, with content that can be varied as close to real time as possible. This is also where a great amount of analog print is done, though in analog format it’s in- or close-line printing. The extent to which digital sheet systems could be configured inline is not clear, though in early years it may not matter that much.
Roll systems seem to have two projected positions. First, a roll-to-roll system could also be placed at the end of the supply chain at the box maker – probably a larger box maker that would benefit from the higher volumes these systems allow. The box maker could bring in uncut, finished rolls of corrugation, put them through the print system, and post-cut to sheet immediately afterward in order to convert to boxes. But a roll-to-roll system could also be placed at the up-chain position of the corrugator itself.
At the corrugator level, there’s a lot of frustration because these companies have worked hard over the years to become both productive and affordable at a high speed. Printing that is done down the line in different formats (sheet or roll), using different print at varying levels of efficiency, creates a formidable tangle. This amounts to lost time and too many human interventions or costly deployment of staff. The dream of some at the back end of the industry is to bring print into ever-closer alignment with board manufacturing, using a digital information flow to coordinate content in real time with current demand and deliver pre-printed products to the converter without the converter having to do the print. Half of corrugated packaging today is supplied by fully integrated houses that both print and create the boxes themselves, allowing for a lot of additional integration of processes.
For printing to be done at the early part of the supply chain, the systems would have to be large and fast. They would also need to be versatile, not just at the highest quality print levels, but also at lower levels.
Many questions remain. Can inkjet technology, which is relatively sensitive to dust particles, even survive in a dirty corrugation plant? Can aqueous inkjet systems print fast and economically enough on coated substrates at high coverages, even at higher speeds? Are the new water-carrier UV systems economically, environmentally, and graphically acceptable to the industry? If the answers are positive – and sooner or later they probably will be – then the potential within a global market of 2.7 trillion square feet is great.