Colour, inks and paper will make or break digital corrugated

by FESPA | 10/05/2018
Colour, inks and paper will make or break digital corrugated

Simon Eccles discusses the featured exhibitors that will feature at the Digital Corrugated Experience at FESPA 2018

The 2018 FESPA event in Berlin incorporates the first FESPA Digital Corrugated Experience. The corrugated industry sector is on the verge of adopting high speed digital printing systems. Although the concept has long been established on adapted flatbed inkjets, these have significantly lower throughputs. Corrugated is big business worldwide, and the trend is for ever higher printed quality demands as corrugated boxes become are increasingly used on retail shelves to carry the promotional and brand message as well as simply providing strong containers. Corrugated display and POS items are also growing in popularity, though they represent a fraction of corrugated production compared to boxes.

Digital printing allows for higher efficiency due to the elimination of the plates and make-ready times needed by non-digital flexo and litho presses, and it also allows for variation of the image within even long runs.

Sean Moloney is speaking at the FESPA Corrugated Experience every day (at 11:30). He’s the global product manager for Corrstream66, a high speed inkjet board printer developed by Sun Automation in the USA. Corrstream can run at 70 metres per minute – typical throughput is up to 4,500 sheets per hour (of standard 3 x 5 foot size).

Caption: HGS Packaging in Bradford, UK, has the world’s first Sun Automation Corrstream66 press.
Sun Automation is one of several manufacturers to develop high speed inkjets for corrugated sheets (or boards). Barberan, Durst, EFI and HP are the other main players, though it is early days for any of them in terms of sales. All of them cost several million Euros per press, so this is not a trivial investment in a market that’s only just starting to look at ways of taking digital from its current flatbed status as a producer of sample packs or at best very low runs for special jobs.

Moloney explains his aims for his presentations: “At FESPA I am presenting each day on colour management and ink sets. It will cover what we know strategically with our press and with our technology, but equally what we what we know about the industry and where the three main ink types fit together: true aqueous as I call it these days, then UV and hybrid. We're not here to say that we're good, they're bad or anything like that. Every version of this technology has a place, I believe, across the full packaging space. In corrugated, it's certainly true. It's a decision that the market and the customers within those markets will ultimately have to make.

“My presentation will be in business and solution language, rather than trying to sell a piece of kit. I spent 25 years making boxes and I like to think I know what the box makers need to hear, even if that's not what they expected to hear! People want to make money out of boxes.”

Moloney’s main theme is that while the mechanical challenges of high speed digital corrugated printers have now been largely overcome, by Sun and its competitors, it is the inks and their interaction to the corrugated substrates that will really count with potential users.
Aqueous versus UV

CaptionEFI uses six UV ink colours on its Nozomi C18000 corrugated machine.
Sun Automation’s Corrstream uses what he calls “true aqueous” inks, rather than the UV inks used by Barberan and EFI, or the aqueous-UV hybrid “Water Technology” inks used by Durst in their high speed corrugated printers. HP also uses aqueous ink in its C500 high speed corrugated sheet printer.

HP also uses an aqueous ink on its PageWide T410S single-sided high speed web-fed inkjet and the T1100S 2.8m wide inkjet that’s a joint venture with KBA, both of which print onto liner paper (rather than pre-formed corrugated sheets or rolls). The forthcoming BHS 2.8m liner printer being developed as a joint venture with Screen, also uses aqueous inks and an aqueous varnish. However, liner printers are a separate market with different potential users than the high speed sheet printers that Moloney is talking about at FESPA.

Barberan got into the high speed corrugated sheet printing market several years ago and has several installations. Durst has announced two sites with its high speed Delta SPC 130. EFI has five announced sales of its Nozomi C18000 corrugated machine (some with multiple presses). HP has announced two PageWide C500 sales. Sun Automation has one Corrstream user site (HSG Packaging in the UK), which went live in 2016.

While there’s a lot of interest in the corrugated market, the big users are holding back to see what happens, Moloney believes. “The early adopters of do completely understand the bigger picture and they are taking advantage. HSG is like the Skunk Works for the large groups,” he says. “The bigger groups just take time getting into this, whereas smaller entrepreneurs get it and they move with it.”
Recycling and gluing
Sun Automation’s (and HP’s) use of aqueous should give an advantage in the packaging market, Moloney argues. It’s not just the obvious questions about UV in relation to food packaging, he says: “Anything to do with UV, any particulates that show themselves up, whether it be hybrid or full UV, is still giving people a nervous position, even if claims are made that they are low migration. What we see people are frightened of is not so much the near term in terms of UV POS or display work that isn’t food related, or even small batches of secondary packaging that's food related. The problem is when they try and recycle the UV printed corrugated. As that comes back into the supply chain, it's going to be infiltrated full of particulates.”

Another UV challenge that Moloney highlights is gluing: “The vast majority of boxes are glued water-based PVA, for the same reason that we use recyclable inks, starches, paper in corrugated. This where UV causes a problem. The challenge with PVA when you're printing on to a UV varnish surface is that it doesn't adhere. So you have to then design an ink-free or varnish-free space for the glue lap. However, with some designs you need to cover the box for the design. So again in our opinion the opinion water-based ink takes away that problem.”
UV has the big advantage of working with standard corrugated paper substrates and producing consistent colours that aren’t affected much by absorbency. Aqueous inks by comparison can be absorbed more and spread into “uncoated” papers (ie those without a special inkjet-receptive coating), which carries the danger of blurred images and paler colours. Special coatings solve this, but add to the cost, as they either have to be applied by the paper mills, or added at the print site as a pre-print coating stage.
Colour gamut breakthrough
Hence Moloney’s particular desire at FESPA to stress that colour management doesn’t have to be a problem for aqueous. His message is that that just because inkjets can’t print the “spot colours” commonly used by non-digital flexo and litho corrugated presses, doesn’t mean that they can't match all the brand colours. Indeed, the Sun Automation Corrstream only uses four inks – cyan, magenta, yellow and black, but these can achieve a much wider gamut than flexo or litho CMYK, Moloney claims.

“I think there's a lot of confusion about what's possible in terms of colour management, as you take each step through these processes onto different substrates,” he says. “The normal route in the industry is to add more colours. Light cyan or light magenta is often how you take a gamut to a wider position when it comes to let's say UV ink, because there's not too much of an interaction between the ink and the paper.

“When it comes to aqueous, which is obviously our strategy, we're finding that we're able to position a wider colour gamut using only four colours, if we work with the right papers. That may be obvious but, doing that on the ground in practical supply chains is a wholly different matter. The main message is that with true water-based inks we can say confidently that with four colours, not six or eight, we can reach a high percentage of Pantone colours.”

Aqueous inks certainly cost less than UV, but a common belief is that because there is no solvent or water to be evaporated, then every drop stays on the paper so the cost per unit area is comparable with aqueous. Moloney claims that this is too simplistic. “It's early days and it might be construed as bias, but I try not to be. But as far as we can tell, if you want to extend your gamut out on anything to do with UV ink you have limited options, because the papers don't have that much of a say. If you bring true water based inks into play, which by the way are more friendly when it comes to the environment, then you do have a position where you're able to take a significant reduction in the amount of ink being consumed to gain the same colour gamut, and that's driven by the paper. This is much more complicated than many people first think – if you go into a position of the capital into a supply chain that is already margin-intensive and has a natural fear of the price of ink. The machines we’re talking about use a great deal of ink. People have to understand, not just the position (which is very important) about the future of their investment and how it will sit, but also the detail in how much ink they're actually going to be using every day to achieve what the markets still expect, which is spot colours.”
Joining the dots
This then leads back to the relationship between the ink and the papers it needs to work properly. “Paper makes up about 50% of the cost of the product,” Moloney states. “If you don't understand how to join the paper and the ink and do that in such a way that makes it efficient in terms of the cost of ink on the sheet, then you end up with a situation where people just cannot see a future for this technology.

“The assumption that you're going to use more with water than UV because of absorption is not necessarily true if you use the right papers. Because we do understand paper we're able to manipulate the papers towards not only the technology but the inks. That’s exactly what's going on right now with ourselves and HP, who use true aqueous. HP seems to be concentrating on uncoated papers, while we’re looking at coated. It's the coated development that provide not only ability to print gloss but also the ability to be much more efficient with your ink.”

Costs can come down in other ways, he says: “Because we don't touch the substrate, a lighter weight liner is possible. So that means we're able to get more per tonne.”

On the other hand, Moloney says that the assumption that the non-contact nature of inkjet will eliminate flute shadow (the lighter and darker stripes of print corresponding to the flute pattern) isn’t true, though it’s much reduced. “Digital does not eradicate flexo shadow. It's a consequence of the way the paper and flutes are produced, if they over-starch it or burnish it. It's not just down to the press in terms of the pressure they put it on a flexo anilox, it’s how the board is made and how they use it.” The problem is most pronounced with the larger flute sizes, he says. “So what we do is to use microflute or E flute on top of a wider flute, say B flute or C flute, to give box integrity. While non-touch print does help, anybody who tells you in inkjet that they're able to eradicate flute shadow because of the process is not telling the truth.”
Engaging the mills
The next stage is to get suitable papers into the market, Moloney says. “It is absolutely clear that a huge amount of the responsibility for output goes onto the paper. We have achieved that, we can dry the inks, we understand the gamut, we understand the outputs, we know we can handle it within our technology. The next phases, and HP is in the same place, is commercialisation of that paper in terms of cost per tonne. And that's a that's a symptom of a supply and demand or chicken and egg. It's not that the technology can’t do it, it's a case of the supply chain bringing it into play.”

This is going to rely on the big corrugated printers going to the mills with potentially huge orders that will bring the coat of coated papers down, he say. But it’s a chicken-and-egg situation, he admits, as the big printers aren’t going to be terribly interested in aqueous digital unless and until the paper cost comes down. However, having fast digital corrugated printers out in the market and functioning will start to concentrate minds at both ends of the paper supply chain he believes: “Now that we've been able to go out and sell machinery we can bring clients and prospects into conversation and then that the paper mills will wake up, because then they realise just how much volume demand will be needed by a big sheet plant. That isn't finished but it is the phase that the industry needed in order for this technology to become a reality. And it's that message that we now need get across to the industry.”

To find out more about the Global Print Expo, see the full exhibitor list and to see information about how you can register to attend, visit the event’s official website:

For free entry use code FESJ801 when registering.

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