Ruco’s ink series 935UV-LED are for the decoration of hollow and flat glass. 935UV-LED inks are suitable for LED curing and can also be used with hybrid systems.

In times of surging energy costs it comes as no surprise that the glass decoration industry is interested in energy-efficient manufacturing techniques. The use of LED technology with screen printing inks is a promising option in this context. Based on its 935UV ‘flagship’ series of screen printing inks for glass decoration, Ruco is now also offering an LED UV-curing version.

In addition to being a potential cost-saving factor, the 935UV-LED inks also enable shorter production cycles and improved process security, while offering the same benefits with regard to resistance characteristics, opacity and brilliance of colours.

In contrast to conventional inks, which require subsequent post-curing of at least 24 hours, cross hatch testing can be carried out immediately after printing. According to the company, 935UV-LED inks offer advantages with regards to environmental and safety aspects.

Benefits of the technology

Conventional UV bulbs like those in mercury vapour lamps cure UV inks within the UV-C and UV-B spectrums comprising wavelengths of 100–280 nano­metres and 280–320 nanometres respectively.

By contrast, LED UV lamps have a narrow spectral output, most commonly at 365 or 395nm with +/-20nm at peak wavelength. LED-modified UV inks contain additional photoinitiators that have been tailored to react at these specific wavelengths. Thanks to this primarily chemical reaction in the long wavelength spectrum, LED UV systems can achieve excellent depth of cure, which results in better adhesion on the glass surface directly after the printing and curing process.

When using conventional UV-based systems, the glass will require a post-curing process, which means that users have to wait between 24 and 36 hours before they can check the adhesion of the ink film on the glass surface. With UV LED inks, this can be done immediately after curing.

Due to their good depth of cure, UV LED inks allow for greater layer thicknesses, which results in higher opacity. This is beneficial both for difficult substrates and for the application of difficult colours. When compared to ceramic inks, which must be exposed to high temperatures during the curing process before the final colour can be seen, users can check the colour accuracy of UV LED-based inks directly after curing.

Ink curing by means of UV LED is a new technology. The use of light-emitting diodes offers advantages compared with conventional systems, with lower energy consumption being a major factor. LEDs do not create ozone so that the need for expensive exhaust systems is eliminated, plus they have a long service life.

The use and application of UV LED printing inks cannot and is not designed to completely replace the use of conventional UV printing inks and ceramic inks. However, in many cases UV LED curable inks can provide a suitable alternative, bringing with them environmental benefits as well as new decorating opportunities.

Meanwhile Ruco’s standard UV-curing 935UV inks are extremely popular among users. Its two-component inks are suitable for multi-colour inline printing and feature resistance to chemical, alcoholic and cosmetic fill products as well as good dishwasher resistance. Curing under standard UV bulbs, these inks eliminate the need for thermal post-treatment in the form of time-consuming and expensive oven drying. This allows for more streamlined and cost-effective decoration processes.

From a visual point of view, the 935UV series opens up design opportunities. In addition to the basic inks, which offer high opacity and brilliance of colours, there is also a wide range of special-effect inks available for achieving matt and frosted finishes as well as metallic and glitter effects. These inks are used, for instance, for decorating flat glass for gaming machines, furniture or shower doors, and also when it comes to hollow glassware for the cosmetic and other industries.

Unlike ceramic printing inks, these UV inks can also be used for realising special embellishments using fluorescent and transparent colours as well as four-colour images – such opportunities are attractive especially for image-conscious segments such as advertising.

In addition to screen printing inks, Ruco will also be presenting its T28 pad printing ink series at glasstec. They are glossy, physically drying and chemically reactive two-component inks suitable for printing onto glass and metal and satisfy the demand for mechanical and chemical resistance, as well as for high flexibility.

Ruco Druckfarben will be at the glasstec trade fair in Düsseldorf, Germany, Stand A30, Hall 12.