Touchscreens are an interesting opportunity for the field of printed electronics. As home appliances become “smarter,” consumers expect more from their devices. Touchscreens are the interface that allows users to use their smart phones and tablets, and program their refrigerators, washers and dryers, ovens and much more.
 
Ink manufacturers have been working with membrane switch manufacturers for years, and are developing inks that can now provide more functionality.
 
Headquartered near Stuttgart, Germany, Marabu GmbH & Co. KG is a leading global manufacturer of screen, digital and pad printing inks. Katharina Rogner, marketing and communication, Printing Inks for Marabu GmbH & Co. KG, said that the company’s inks are used for membrane switches as well as home appliances, which led Marabu to look into the touchscreen field.
 
“Manufacturers of membrane switches with whom we’re working successfully for a long time are a key market for us,” Rogner said. “We also serve the market of household appliances, where 3C (computing, communication and consumer electronics) appliances are strongly demanded.”
 
The use of capacitive touch interfaces is on the rise for household appliances’ touchscreens. Screenprinting allows printers to add special effects and functional layers when designing capacitive input systems. Rogner noted that decorative inks used on these screens need to show a high level of resistance, ensuring the input system operates correctly. The screen itself is made of a single plastic panel, instead of multiple layers.
 
The inks must provide resistance to chemicals, water vapor, and high and low temperatures, as well as attractiveness to the consumer.
 
Marabu Inks has designed solvent-based and UV-curable inks for touchscreens. On the solvent-based side, Mara Switch MSW opaque black 181 is a specially formulated nonconductive shade of black with extremely high electrical resistance, designed for front panels, according to the company. Marabu has also introduced transparent varnishes that can be backlit by LEDs.
 
Rogner noted that the use of UV-curable inks is increasing in this field. UV inks are solvent-free, thus eliminating emissions, and UV ink systems have short drying times. Since UV inks do not clog mesh screens, more intricate lettering and symbols are available. Marabu designed its Ultra Mold UVPC series of inks for this field, and the company is working on a UV-only solution for plastic panels.
 
Rogner said that Marabu is seeing interest in its new products for the touch screen market.
 
“We always gain very positive reactions at fairs and from our customers as well as from our development partners,” Rogner noted. “They appreciate our open minded philosophy for new applications and developments. One of our latest development projects is, for example, a combination of screen and digital printing onto front panels.
 
“We are still busy improving our solutions of screen and digital printing combinations,” she added. “We also also working on new developments, such as UV inks for glass. New silicone-free shades of varnishes shall be available for special glass applications.”
 
Marabu Ink’s experience in the field of screen ink is an important asset in the touch screen market.
 
“Marabu is a company with a long history,” said Rogner. “The ink manufacturer manages to be always on the pulse of time. We set milestones with plenty of industry-first solutions, especially in the field of solvent- and UV-based ink systems for screen and digital printing,” Rogner noted. “Our long-time expertise helps us to be a strong and competent development partner in projects with material manufacturers and customers. We often develop our ink systems in cooperation with great attention to our partner’s needs.
 
“In the 3C market, there are often requirements of ink systems which have, for example, a high opacity and a high electrical resistance,” she added. “Marabu offers ink systems for this special purpose as well as inks and coatings for the decorative parts.”