Abstract: The present invention relates to a reactive sol-gel ink for printing a metallic substrate, preferably for a coil coating process, comprising 10 to 30 wt % of a sol-gel resin composition and at least one pigment, preferably at least one yellow pigment, at least one purple pigment, at least one cyan pigment or at least one black pigment. The sol-gel ink of the present invention can be used in a digital print process, preferably using ink jet means, as a mediator of covalent bonds between a print layer formed by the sol-gel ink and metal oxides and/or metal hydroxides on the metallic substrate and/or hydroxyl groups comprised in a base coat layer covering at least partially the metallic substrate and/or hydroxyl groups comprised in a top coat composition covering at least partially the sol-gel ink.

Abstract: The present invention relates to a switchable see-through luminescent system, e.g. for luminous signage, characterized by its mode to exist in two different states, transparent (‘off-state’) and luminescent (‘on-state’), due to the presence of a luminescent material (20), coated on to the transparent surface (10), capable of being excited on command by means of lighting sources (30) (e.g. LEDs) characterized by suitable emission spectra. In the off-state of the luminescent material (20), the surface appears transparent and it is not evident any significant modifications of the optical properties (transparency, color, etc.) of the surface.