Printing functional finishes
Madelaine Cornforth talks to Thomas Ruchser, Global Manager of Digital Printing and Carpet Solutions about the company’s developments in functional inks and finishing.
Today there are textile finishes for almost every challenge thinkable. Hydrophobic, anti-microbial and flame-retardant finishes are among some of the most popular for the apparel, home textiles and soft signage industries. For example, functional finishes such as these can be added to clothes to make the wearer feel more comfortable and to keep them dry, while other finishes soften bed linen, make tent canvases flame-retardant or protect upholstery from damaging. However, TANATEX asks the question: “How do you apply them to specific parts of your textiles in one run?”. The company’s experts are working on the answer and found a promising chemical solution to integrate functionalised finishes by digital (valve jet) printing on to fabric, according to TANATEX.
In valve jet printing, the print head nozzles are fitted with individual valves, which can be opened or closed as an ink drop is required. “We have developed a jettable compound as basis for applications,” says Thomas Ruchser, Global Manager of Digital Printing and Carpet Solutions at TANATEX. “It guarantees a smooth run ability of valve jet for hours – just mix the compound with water and add the needed chemicals to achieve functionality.”
The company decided that valve jet, rather than inkjet was the best technology to provide a solution to only printing in certain areas due to the technology’s flexible pick-up being higher than inkjet. Additionally, with valve jet, ‘existing standard chemicals can be applied,’ with no need to create new ones for already available finishes, says Ruchser.
Global Manager of Digital Printing and Carpet Solutions
Functional finishes need to meet several requirements for printing. Ruchser notes that these are:
- Rheology suitable for jetting (shear thinning property)
- No drying during jetting and over run length
- Variable viscosity, depending on requirements
There are many advantages of using ‘functionalised inks’ for valve jet printing to finish certain areas of a textile to give it added function. Ruchser says: “Digital textile printing creates ultimate flexibility. Today, textile manufacturers can print all imaginable patterns on textiles, independently of repeating patterns. Countless designs can be produced without chemicals and fabric wastage.
“Moreover, the adjustment of the printing system and the alignment of the printing templates that are so time-consuming have become a thing of the past. Imagine the flexibility a user will have in applying several functionalities on a selected part of the fabric, or integrated in the design,” Ruchser continues.
Examples of this include anti-odour finishes for the armpits of a garment, insect protection at the inside of a collar, stain repellents applied to the front of a shirt, and anti-abrasion for the elbow zone, Ruchser notes.
These would all be done in the same run or personalised for specific customers. “This saves a lot of time and considerably reduces the consumption of water and chemicals and the contamination of wastewater,” says Ruchser.
Other possible applications include medical, technical or home textiles, such as:
- Thermal effects (cooling, heating)
- Moisture management (water/oil repellence, hydrophilic effects)
- Odour control
- Optical effects
One specialised development that TANATEX has been working on is ‘functionalised inks’. Currently the company’s BAYSCENT® product has a range of different scents available. The possibilities with this technology are endless when it comes to application, such as lavender scent on bed linen or a lemon on the textiles of a car seat to work as an air-freshener in the car. Ruchser explains: “Applications would be similar to regular finishing applications via foulard. The advantage is that the finish only needs to be applied on one side and it can be applied only where needed.” The company has been using Zimmer Austria’s Chromojet technology to apply the inks. “We felt it should be possible as well to add functionalised finished via valve jet printing onto textiles,” says Ruchser. “So, next to the known printing process utilising colour, we are applying a functionality onto the textiles where it is needed. Examples are anti-odour finishes for the armpits, or every scent you can think of (a separate finish, not an ink).”
Additionally, to print a finish no pre-treatment is needed, and post-treatment depends on the specific finish used and all colours and patterns are possible, says Ruchser.
TANATEX ensures colour vibrancy and fastness whilst adding functionality as the finishing is applied during the last (different) step of manufacturing. Dyeing or printing should be done in a previous step.
By Madelaine Cornforth 10 September 2019