Taking a closer look at inkjet developments

With the IMI Europe Inkjet Ink Development Conference taking place on 13-14 April, 2016, WTiN’s Tansy Fall caught up with IMI Europe’s Managing Director Dr Tim Phillips to discuss the conference and also take a closer look at the progress of the digital textile printing industry, with a particular focus on inks.

Hear an audio version of this interview

Hear an audio version of this interview

IMI Europe’s two day technical conference (click here for the programme) delves into the materials, equipment and techniques that are necessary for digital printing ink development and manufacturing. The event is aimed at ink developers across different applications, including textiles, and the conference gives attendees access to key suppliers and an insight into the current technology developments from the inkjet sector. As IMI Europe say, it is “everything that you need to develop and manufacture inkjet inks.”

Tim Phillips added: “We have a range of speakers talking about the technical aspects of ink from the raw materials to the processing and characterisation, and then some case studies about how inks are being used in various industries.”

Phillips has a wealth of experience working in the inkjet industry, having been at both Xennia and Sensient before moving to IMI Europe and also setting up his own consultancy business, Catenary Solutions. Having participated in the development of the industry, Phillips is well placed to predict which technologies we might see transferring into textiles from other areas of the inkjet industry. He commented: “A couple of things we’re starting to see at the moment. Firstly, the growth in single pass printing. […] It’s a very interesting technology and, from an ink point of view, what that does is call for a much higher ink reliability, because if you’re printing in a single pass, and you have nozzles dropping out, then that immediately shows up in the print. That calls for more detailed development from the ink guys.

“Pigmented inks is also a key area, which is being discussed at the IMI Europe conference. Pigmented ink has some promise for textile printing because it offers the opportunity to print onto a wide variety of fabrics with the same ink. The challenge is that it requires a very high pigment dispersion quality, and innovative binder chemistry that is being worked on at the moment in the industry.

“The third thing is new printheads and again we’re starting to see that. There has been one printhead that has been dominating the high end machines over the last few years, and other companies are trying to move into competition with that head.”

Where is development still needed in digital textile printing?
Phillips said that in the next five years we are likely to see inkjet being used not just for colour printing on textiles but also functional printing. He said: “There are some examples of this around at the moment but I think this is an area that in five years’ time will look very different. [All of the functional applications] call for specialised inks for depositing those materials onto the textiles.”

Despite this clear scope for growth in the textile side of the inkjet industry, with more and more companies from the graphics sector entering into this market, Phillips also recently explored the key issues that are holding back the inkjet industry’s development. This included: the trade-off between application performance and printability, which Phillips elaborated on: “Everyone wants to make the inks more highly coloured, so you can put down brighter colours in one pass of the print. The trade-off there is that as you do that you make the inks more difficult to use. You potentially make them less reliable.”

Characterisation and quality control are also issues for the textile side of the inkjet industry, getting the right equipment and using the correct techniques, and making sure that you follow that all the way through the manufacturing process. Phillips said: “Keeping this aspect under control is very important. Some of the really big textile ink companies have come badly unstuck in quality control in the past and it can cause huge issues for them and their customers.”

Another issue that the industry needs to overcome through development is related to application of the inks. There is a huge trend in the digital textile printing sector towards the creation of one ink for all substrates and some of the key market players are already offering their solutions. However, as Phillips expands: “There is still a lot of work to be done in that area. I think most people would argue that those inks are not ready for all applications. They are suitable for some applications at the moment but not for all. That’s an area that needs to be worked on.”

Phillips also expounded on importance of dispersion quality, which is central to the newer pigmented inks coming onto the market, and to the creation of ink that is suitable for all substrates. “Getting very high quality dispersions is fundamental to making those inks work reliably.”

“The issue is that you’re fighting against physics. You’re trying to make something stable that isn’t naturally stable. So if you put some sand into some water, for example, the sand sinks to the bottom and doesn’t mix together well. But that’s really what you’re trying to do, you’re trying to make a material that is like sand in water behave like a single fluid that will go through pipes and printheads every single day.”

“If you have a dye based ink, those colorants are completely dissolved in the ink. It makes for a very simple ink construction compared to an ink that has these particles in it. So sublimation inks and pigmented inks have this extra challenge.”

Tansy Fall

This article was originally published on the WTiN website (free subscription required).