Another interesting presentation at the 21st European Ink Jet conference run by IMI Europe was from FUJIFILM Speciality Ink Systems. Jon Harper-Smith described a new hybrid UV ink technology that they have been developing.
A trend in ink jet is towards higher resolution printheads, which tend to require low viscosity inks. At the same time the range of applications for ink jet is growing, and with it the range of substrates that users wish to print on, requiring increased functionality of the ink which tends to increase the ink viscosity.
Conventional UV-curable inks consist of monomers, polymer/oligomers, and other additives. Basically the functionality comes from the polymer/oligomer and the viscosity from the monomer. It is hard to balance these to achieve the required performance. In addition all of the volume of the ink is left on the substrate surface, which can lead to undesirably thick layers for some applications.
The new ink consists of solvent, to adjust the viscosity, and a special hybrid polymer to create the functionality. After the drop reaches the surface, the solvent (which can be aqueous or a volatile organic solvent) evaporates to leave a smooth even film. This is then cured using a UV light source as usual.
The ink is free of monomer, which is important for food industry applications. Because the image is flatter than normal UV-curable inks the print quality is claimed to be higher, and this should suit consumer applications such as labels.