The majority of inkjet printing on textiles is carried out with colourful dye-based inks. Dye sublimation printing makes up around 50% of the market, with reactive dyes following in second place. And, in the last few years, much development has been focused on inkjet printing of pigment inks, with significant steps having been taken to commercialise the process. Pigments are problematic due to their reliance on a binder and the difficulty of passing them through a small inkjet nozzle. However, these issues are swiftly being overcome. The industry’s ever-progressing success in tackling pigments has catalysed exploration of other applications that might be possible for inkjet printing on textiles.
In the industry, there have been musings on whether inkjet could achieve enough saturation to replace the dyeing process, though this is not something that is on the horizon quite yet. And, liquids with high viscosity, for both technical coating of textiles and pre-treatment ahead of colour inkjet printing, have been a topic of interest. There was a suggestion that Tencate’s Osiris printer, the IP for which is now owned by EFI Reggiani, may be revitalised for this task but that is yet to be seen. Moreover, a problem arises in that standard inkjet print heads, whether they are recirculating or not, are not likely to be able to cope with such high viscosity fluids.
In response to the print head problem, a number of companies in the market are beginning to look at ways in which inkjet technology may be adapted for this application. One such company is Archipelago Technology, based in Cambridge, UK. The company’s Powercoat and Powerdrop systems have been designed to jet any difficult substance for a number of applications, one of which is textiles.
Speaking to WTiN about this technology, Archipelago CEO Guy Newcombe says: “When we started Archipelago, we went out and asked customers what they really needed. One need that came up again and again was for a machine that could print glue. As we dug deeper, we saw this was a very widespread need. Glue is inherently sticky and tricky to handle but in modern manufacturing it is used everywhere. Cars, shoes, furniture and even Dyson vacuum cleaners are held together with glue. But how do you jet something that is inherently sticky and viscous?
“We recognised that we’d need a bigger nozzle than is used in most inkjet printers and more energy to push it out. Also, it’s hard to pump glue around so the glue feed path would need to be short. Over an intense 12 months we established the fundamental design and operation of the system. The principal component is a precision print drum which contains precisely machined nozzles. In operation we first fill the nozzles with glue, then rotate the drum and then eject the adhesive with compressed air. By controlling the different variables, we get a good control of the ejected drop of adhesive.”
Newcombe has worked in the inkjet sector since the early 1980s, when he was employed as a summer student at Domino Printing, UK. “They were a young pioneering company building the market for inkjet products,” says Newcombe. “It was a wonderful experience, and I met Graeme Minto, the founder, and saw how he built and grew his team. Once I’d finished my degree and PhD, I joined TTP, which was also a pioneering business. There we invented and developed two other inkjet technologies – one that made very fine drops and another that printed very detailed images.
So, when we started Archipelago Technology, we had a team with over 25 years’ experience of creating new inkjet technology and delivering products to customers.”
Having developed the Powercoat and Powerdrop technologies, Archipelago’s first customers have been OEMs building machines that deposit glue without contact, for large scale, high throughput production. Going forward, the company is looking to engage OEMs in multiple industries, textiles being one, with the objective for the Powercoat technology to be used for numerous high viscosity applications.
For the textile industry, Newcombe says: “We are configuring the design for two main families of applications: patterns of distinct dots, which is Powerdrop, and continuous coating, which is Powercoat.
“If you look at the textile industry, there are many places where adhesive is used to bond different layers. A good example is bonding Gore-Tex membranes to waterproof clothing. Powerdrop is perfectly suited to this, as it puts down a network of dots with air gaps to let the fabric breathe. Then we also see Powercoat being used to put down additional functionality, for example stain resistant coatings and antimicrobial layers.”
Archipelago has already been approached by some key players in the textile market and Newcombe said: “We’re already designing and building systems for customers in high throughput, specialised applications, including textiles. But we want to do more, and we are talking to other customers who want to put down adhesive layers, protective coatings and textures.”
There are still some barriers that will need to be overcome in order for the Powercoat inkjet technology to be used for technical coating of textiles. Newcombe says: “The skill is picking the right launch applications and making sure you are involving everyone in the supply chain in the scale up process. When the ceramic industry moved into inkjet they made the transition as easy as possible. We’re copying that model by making systems modular, drop in replacements on the production line, minimising disruption and making adoption easier.”
At the moment, Archipelago is currently engineering its Powerdrop print engine for specific applications, including machines that lay down glue, metallic paints and UV coatings onto a broad range of substrates. This includes plastic films, paperboard, metal and, of course, fabrics. “The focus is in taking customers materials, putting them down where they want them, and nowhere else,” adds Newcombe.
Source: www.wtin.com