Unlike solvent and most aqueous inkjet inks, UV curing inks that perform day-in, day-out are hard to replicate by third parties. This is because they contain a lot of ‘big science’ involving UV wavelength sensitivity, nano-particles, photo-initiators, dispersion technology and a marriage with diverse printheads that is hardly the same twice. Andy McCourt visits the world’s centre for inkjet UV, Fujifilm Speciality Ink Systems (FSIS) in Kent, UK; formerly Sericol.
The name Sericol has loomed large in the world of screen process printing since 1951 when, having escaped his war-ravaged country, a Hungarian émigré, Alexander De Gelsey, established the venture following a Cambridge degree and two years in research with Kodak.
De Gelsey’s drive and passion for colour in both photography and print, created a remarkable global brand that rose to dominate screen inks through R&D and sheer quality. 1968 saw the development of the first thin-film solvent screen inks that catapulted screen process into viable high production. This was followed in 1978 by the first UV curing screen ink and again in 1999 by the first digital UV ink, which Mike Battersby, marketing manager for wide format at Fujifilm Speciality Ink Systems (FSIS) – owners of Sericol since 2005 – admits was “a product looking for a market” at the time. Cambridge-based partner company, Inca Digital, soon solved that issue with the introduction of the world’s first flatbed UV presses.
Following ownership by Burmah Oil and later BP, Sericol was acquired by Fujifilm one year before the passing of its founder Baron (he was an aristocrat) Alex De Gelsey. He would undoubtedly be proud to witness the modern, extensive plant at the place where he relocated it from London to Broadstairs, Kent in 1960. Indeed, many employees have clocked up well over thirty years service and recall the founder’s era.
World’s largest digital UV ink plant
Visiting the place that pumps out the lifeblood of a huge industry is a humbling experience and one that drives home the merits of using only the best designed and tested inks through expensive digital printheads. FSIS makes inks for the Inca Onset printers and for both its own Acuity flatbed UV printers (Uvijet), plus the related Canon-Océ Arizona devices. Additionally, there is further OEM manufacture, the names of which are kept a close secret. Add to this LED UV inks which FSIS pioneered; on-going manufacture of solvent screen and plastisol inks plus narrow-web label inks both for the screen & UV flexo print processes
Dr Seán Slater is development manager at FSIS. With the constant changing of printhead technologies and myriad substrates needing to be printed, he admits it’s a challenging task. “We have around eighty basic ink ranges with 1,300 formulations – each printhead requires a different UV ink. Then applications can vary, such as our KV inks for thermoforming; they need to be stretchable and heat-resistant. On top of this is the increasing demand sector-by-sector. FSIS has received seven factory upgrades in the past six years alone, including a five million Euro (AUD $7.3M) refit in 2013, and we have plenty of scope to increase production further.”
It can be no wonder that, as well as the award-winning Broadstairs UK manufacturing facility from where nearly 6,000 tonnes of ink a year is shipped to 86 countries, Fujifilm has another custom built R&D laboratory in Japan, employing 1,200 people. As a group, Fujifilm is spending AUD$8.8 million every day on R&D alone. Over 100 ink patents have been filed just in the past year.
Because of the exponential growth in UV curable inks (15.7% per year from 2015-2020 according to an Allied Market Research report), FSIS is devoting the major part of its efforts in this area. “We believe UV technology will dominate inkjet because of lower cost, higher productivity and more applications,” said Dr Carole Noutary, FSIS digital inks development manager. “Our innovation made UV inkjet a reality, FSIS pioneered UV wide format inkjet technology.”
From micro to nano
“Making conventional pigment ink and toner requires micron-sized particles,” explains Dr Slater. “Digital ink for inkjetting is at the nano-level. The chemistry at this level is challenging as pigments have a tendency to agglomerate – clump together – and settle due to gravitational effect in the pouch or container.” FSIS has a proprietary milling and dispersion technology called MicroV that breaks down the particles to less than 200nm, which is smaller than a human cell. Each nano-particle is then coated with a dispersion coating to prevent agglomeration. The particles actually repel rather than attract each other. Polymers, photo-initiators, oligomers and other liquids are added and precisely mixed to create the finished UV ink for optimum jetting, colour saturation, gamut and stability.”
The result is ink matched to particular printheads, both Fujifilm’s own Dimatix range and others that enhance jetting reliability. It has a longer shelf life and exhibits an unrivalled vibrancy of colour. Seeing the process in action at Broadstairs is a marvel to behold but many of the techniques are IP-protected and, understandably, could not be photographed.
“Packaging and shipping is equally important; average shelf life for UV inkjet inks is twelve months and storage temperature can affect this,” said Battersby. “We test our inks at forty degrees centigrade for four months and retain samples from batches in case later problems need to be investigated. As UV ink ages beyond shelf life or is improperly stored, viscosity could rise and jetting problems can happen. Although the white inks have been formulated to minimize settling, the very dense pigment will sink to the bottom of the pouch eventually. We always recommend agitation of white ink pouches before installing.”
The QA testing that goes on at FSIS is astonishing. Inks are printed on numerous substrates through various printheads; abraded, stretched, stacked under pressure, measured for spectral response, scratch-tested for adhesion, cured with varying UV wavelengths and examined optically as droplets emerge from minute ink nozzles to check velocity and satellite formation. It all adds up to very high quality UV inks.