There are quite a number of digital packaging printers around now. Most are aimed at the folding carton or label markets, with a few targeting flexible films, and a couple aimed at corrugated board. Last year I visited the Czech Republic to see HP’s T400 Simplex, a variant of its Inkjet Web Press designed for printing corrugated packaging. Obaly Morava is the only independent Czech producer of corrugated board and packaging and was the first company worldwide to install this printer.
It is a family business, led by CEO Martin Rehorik, with around 250 employees. The company started by outsourcing the corrugated production but in 1996 installed its first corrugating machine. A few years ago the company invested in a Bobst Master Line for production and converting of corrugated packaging with flexo printing and die cutting, followed more recently by a Bobst Expert line.
But as Rehorik explains: “Three or four years ago our sales reps told me that we needed to improve the quality of our print to the level of offset. At the same time the European and worldwide prices were still falling and we were feeling the shortening of average orders.”
He realised that he would have to invest in a line to preprint rolls of liner to be added to the corrugated to create a preprinted corrugated board solution. He explains: “When I compared the two possibilities, of lamination or preprinting, I realised how many unnecessary steps lamination would mean for me. It would need a six to eight-colour offset press, with space and the operators plus the paper for lamination, which is very specific.
To eliminate any unnecessary steps, Rehorik opted to print directly to the liner, and then started looking around for a digital solution that would be flexible for short runs, but competitive on price. This lead him to HP, and to the Inkjet Web Press.
The Simplex variant
Essentially this is just a single-engined version of the existing T400 inkjet printer. HP has had to make a couple of minor modifications. Thus the rewinders have had to be modified to take the larger four-inch cores that are used in the corrugated industry. It also gains web cleaners and there are some differences in the software to cope with the substrates and associated colour profiles.
But otherwise it has the same specifications as a standard T400, with a maximum print speed of 182mpm. This equates to around 12,000 sqm/hr. Resolution is 600×600 dpi, which allows it to print text down to four point quite legibly. It uses the same A51 thermal printheads with the same water-based CMYK inks, complete with a row of printheads for HP’s bonding agent.
HP has also had to develop a new priming agent with a coating unit to deliver this. But unlike the bonding agent, which is only printed on the image areas, this unit flood coat the sheets to optimise them for digital use. There are currently two different priming agents, for coated and uncoated papers, with a third being developed for gloss coated papers.
Gianluigi Rankin, HP’s Product manager for Inkjet Web Press Packaging solutions, explains the differences between these options: “Uncoated boards can use bonding agent or priming agent. The priming agent gives you a little more colour gamut and is more economical. But bonding agent is good for low coverages. The bonding agent only goes where we print so on a low coverage job you use very little. For the coated substrates there is only the priming agent.”
Rehorik says that the system works well, explaining: “We can print to any type of paper. We are using a standard type of stock in our corrugator. Because the corrugator has a heated hot plate for drying we are able to control the humidity to the exact level for converting to packaging.”
He adds that one of the immediate advantages of digital printing is that the process is extremely simple, with no need to mix inks, change plates or any other makereadies. It’s simply a matter of sending the file to the press, printing to the liner, adding it to the corrugated board and then die cutting.
Coincidentally, while I was there Rehorik announced that he had just that afternoon taken his first big order for a job to be produced specifically on the T400. Rehorik took a big gamble on being the first to install an inkjet press for this market, and it seems that it’s paying off for him.