The decoration is one of the most important aspects in production process of ?conventional? ceramic: the price of a ceramic article, such as table ware or wall tile, is extremely sensitive to the quality of decoration, in terms of both its design and implementation.

The ?no contact? ink deposition permits decoration of structured and curved surface with high definition images. Ink-jet technology could be a revolutionary innovation because of easier production management, in terms of costs reducing, processing flexibility increasing and high resolution with low pigment consumption. So there are really good chanches for a successful future in the ceramic world for this technology.

Unfortunatly the avaiable inks are the same of traditional ceramic paintings (soluble salts and grounded pigments) at the moment. These materials show strong problem when using in this application.

With soluble salts colours are limited (only light tones are permitted) and corrosions phenomena, toxicity, penetration into the ceramic body and nozzle clogging occur. These characteristics make soluble salts useless for ink-jet printing.

In ?Super grounded? pigments finer the size, more the colour loss. On the other side, the bigger the particles size, more sedimentation and clogging nozzle problems occur. Moreover, the angular grain shape increases the nozzle's erosion

Currently, in the ceramic market, ink-jet printing machines work with super grounded pigments. As we are seen, mechanical corrosion (because of particles size and shape) frequently arise and a continue internal circulation of the inks is requested to prevent sedimentation and irreversible nozzles clogging.

Creating a new series of inks for ceramic industry has been the goal of Cericol Advanced Research Center. In our laboratories a new family of them has been developed. They are made with nanoparticles (ranging in side from 25 up to 80 nm), characterized by a good stability and their rheological properties are expecially designed for ink-jet application.

ParNaSos inks system is made by the classical four extreme terms (cyan, yellow, magenta and black) and our research has been focused to the easy mixing of them for the quadrichromic process.

Here we summarize the advantages of using our nanoink in ink-jet applications:

1. the particles are so little that no sedimentation occurs and the liquid exhibit much more a solution behaviour than a suspension one.

2. the spherical shape of the grains, their little dimensions and the lack of heavy surface angles avoid problems of nozzle abrasion and occlusion

3. since our solvent is DEG (Teb=245°C), there are no problems of solvent evaporation so Parnasos inks are safer for human health and for environment pollution: no toxic substances release and no odor take place.

4. we produce the ink as a liquid suspension directly, without the classical processing wich forms powder, making a dispersion after. So there are not particles aggregation phenomena

ParNaSos inks can be used on three different ceramic substrates: gres, monoporosa and second fired tiles.The four-colour process have been applied with Spectra ink-jet printing machine, the so called Merlin system, that works with four Hot Melt Galaxy AAA heads (fig. 2), heated at 80 °C and with 100 dpi native resolution. Despite the low DPI value, results are very good.

Inks were processed at 80°C to assess the right viscosity. When using inks at lower concentration, temperature can go down to 50°C. Temperature control is the only technical expedient to use.

We are proud to say that ParNaSos inks system is the new reference point in ceramic ink-jet painting