It used to be easy to pick the right inkjet technology for wide-format and superwide-format production: if it was an entry-level wide-format machine you got an aqueous printer and if it was bigger and faster then you got solvent. Then things started to get more complicated, first with the introduction of UV-cured flatbeds then with the introduction of less aggressive solvent inks, variously known as eco, light or mild solvent.

　　Subsequently, the boundaries have blurred further with UV moving beyond its flatbed niche to include roll-to-roll printing too, and what was once the preserve of top-end systems is becoming an option at increasingly affordable prices.

　　HP has now thrown yet another ink and printing technology into the mix: latex printing, which it claims offers the part of the market that until now has been dominated by solvent inks with a new C and significantly C more environmentally friendly option. In this instance, when HP claims the technology is more environmentally friendly, it’s referring to a very broad range of environmental considerations. It’s not just reducing the impact on the planet, but also on the working environment for the operator and the environments and applications that the resultant print can be used in.

　　One of the biggest claims HP is making about its new latex ink technology is that while it can print on to all the media a solvent printer can, it can also print on to some solvent technology struggles with C such as high density polythene (HDPE) C which is becoming increasingly desirable because it can be recycled, unlike the dominant banner material today, PVC.

　　“We’re developing lots of recyclable media,” says HP senior ink chemist, research and development for industrial commercial enterprise Phillip Cagle. “If you’re printing with environmental inks you undo all that good by printing on PVC.”

　　According to Cagle, the worldwide market for wide-format printed PVC banners last year was 695,154 tonnes or 1.6bn m2 C enough to cover several major cities and still have spare. The problem isn’t about the volume per se C after all, no ink and media vendor is going to knock the chance to grab a share of that square metrage and the ink to cover it C rather it’s to do with what happens once the print has passed its usefulness.

　　Alternative substrates

　　“A huge amount of that volume will end up in landfill,” says HP worldwide PSP segment manager large-format media Gianluigi Rankin. And if it all ends up in landfill, it would take up a huge volume of 592,704m3. Rankin isn’t suggesting printers stop using PVC immediately, but is pushing alternatives within the HP media range.

　　“We have PVC, but we also have alternatives,” says Rankin. “That includes HDPE, which is one of the most recyclable plastics. It’s a little more difficult to print on to HDPE and on to Tyvek than it is on vinyl, so we surface treat those materials. It’s not fair to say it’s a coating and it doesn’t, as a coating would, add significantly to the cost of the media. The cost uplift we’re talking about is in the single digital range.”

　　Although HDPE is recyclable, the need for the latex ink to form a strong bond with the substrate means it’s not possible to recycle as you would with paper and get back white rolls to go back through the printer; instead it goes for ‘grey’ recycling to find itself in decking and other coloured plastic products, and eventually be incinerated in an energy-from-waste plant as HDPE has double the energy content of coal. Even in the worst-case scenario of landfill, HDPE doesn’t leach any nasties in the ground, unlike PVC.

　　Back at the printer, due to the way latex printing works there are no VOCs emitted, so no need for solvent extraction and no nasty solvent smell C that’s good not just for the guy running the machine, but it also makes its output suitable for applications that some that solvent isn’t, such as retail and grocery locations.

　　Green technology

　　“The inks are odourless C any smell you may notice coming from the sample pack is the smell from the substrate, not the inks themselves,” says Cagle. “Solvent smells C you don’t want that around grocery.”

　　HP’s attention to environmental detail in the ink system includes the containers for the ink, which in their self-collapsing plastic bag in a cardboard box are similar to wineboxes, albeit recyclable ones.

　　Interestingly, latex ink technology was developed by HP before it began its aggressive acquisition spree in wide-format printing. When development started, the firm’s only products were based on aqueous inks and its thermal printhead technology, as used in the Designjet range. The plan was to develop a machine closer to industrial grade using the technology in-house before it gained access to solvent and piezo technology through its acquisition of Scitex Vision, and subsequently bolstered its technical toolkit with ColorSpan and Nur.

　　But despite those buys, latex ink has still come to market, and like the firm’s other Drupa show-stopper, the HP Inkjet Web Press, it shows that the thermal printheads used in desktop products in their millions can have applications in industrial printing that were once claimed as the preserve of piezo.

　　According to Cagle, there’s a clear reason why: price and performance. “It uses exactly the same thermal printheads as a desktop machine. Those heads give us a speed advantage of two times over the competition at the same price point.”

　　The first latex ink machine in HP’s range is the Designjet LC65500, a 2.64m-wide