Page 38 - Print 21 Magazine Jan-Feb 2019

Digital Printing
Wayne Robinson
Aiming for the top
Digital inkjet printing has come a long way in the last few years, but can it go all the way and topple litho as the king of print? Print21 editor Wayne Robinson assesses the state of play.
From posters to direct mail, packaging, books, textiles, wood, glass, and ceramics, inkjet printing is already playing a major role in print production – with much more to come, if its proponents are to be heeded.
From its early days two decades ago when the Epson wide format printer teamed up with some smart software to produce contract proofs, inkjet printing has been on an unstoppable march across the printing industry.
Today its spread is huge, its applications are myriad, and it
now dominates sectors such as display graphics and book printing
– but the holy grail of offset quality replacement has, to most print business owners, yet to be reached despite it being more than a decade since high volume reelfed inkjet burst onto the market at drupa 2008 with Océ and Screen.
That may change, however, as the technology develops at an increasing rate, and as the technology giants pour vast amounts of cash into their R+D efforts in a race to the top, to
the place where they can replace litho presses which still print two thirds of all Australian print. They are already there in the book world and in other areas such as screen printing, a prime example of a technology that has been almost totally superseded by inkjet.
Commercial offset quality, though, remains tantalisingly out of reach for high speed inkjet – at least judging by the market take up in the commercial world, which has so far resisted its claims. There are a dozen high speed reelfed inkjet print systems installed around the country, but these are in transaction and transpromo print houses, rather than commercial printers. Book printers too have taken to inkjet printing; Griffin Press, for instance, has what is described
book printing system’ with an HP Pagewide monochrome reelfed inkjet line and covers printed on HP Indigo – although that of course is liquid toner rather than inkjet.
Water
The issue that has yet to be fully resolved with high volume colour inkjet is the water, which transports the pigment to the paper. It is this that is proving to be the final obstacle for inkjet to surmount on its way to the top.
Paper fibres expand four times more lengthways than widthways when in contact with water, and at the speeds at which reelfed inkjet operates, a decent amount of water is hitting the stock. The imperative, therefore, is to get that H20 off
the stock straight away – but that is far from easy, and that is what taxes the minds of the developers. The spreading water can cause the dot to gain and can impact on the dimensional stability of the stock.
Book printing is somewhat easier to manage, as there is only one colour (black), and relatively speaking not that much ink on the page, so not much water. The quality demands are also not the same as Vogue magazine, hence the strong take up of inkjet
in the book world as opposed to the commercial world.
Nevertheless developments continue apace; companies such as Océ, Kodak, Screen, Fujifilm, Ricoh and Xerox are all making major developments in reelfed inkjet, with more to come. Océ, which along with Screen was first into reelfed inkjet, has its Stream series of printers, including the Océ ProStream, the inkjet press it believes will hasten a move from litho to inkjet.
The water issue is served by a no contact (and seriously large) flotation dryer, which sees off the water and
Today inkjet’s spread is huge, its applications are myriad, and it now dominates sectors such as display graphics and book printing – but the holy grail of offset quality replacement has, to most print business owners, yet to be reached.
creates a protective polymer layer
to lock the pigment ink against the paper. ProStream runs at 80m/min with the Kyocera KJ4 piezo print heads producing a 1200dpi resolution using 2pl or 5.6pl droplets.
Océ has it printing in a YMCK sequence, which it says improves the colour gamut. According to the manufacturer, the gamut of the inks exceeds Fogra 51 on coated papers and Fogra 52 on uncoated papers. The inkjet heads are water cooled to a constant 35oC. The inks are water based with a polymer surrounding the pigment, which melts during the drying section to create a protective layer above the ink.
It prints across 540mm on a 565mm web, and can produce 35 million A4 pages a month.
Screen’s Truepress Jet520 high- speed, roll-fed inkjet presses now have the new SC inks that allow printing on coated and uncoated offset stocks without priming. It is Screen’s response to requests from high volume digital press users
as ‘the world’s most advanced
38 Print21 JANUARY/FEBRUARY 2019