Ink

#This invention relates to inks, ink-sets, a process for ink-jet printing, ink-jet ink containers and ink-jet printers.

#Ink-jet printing is a non-impact printing technique in which droplets of an ink are ejected through fine nozzles onto a substrate without bringing the nozzles into contact with the substrate. There are basically three types of ink-jet printing: i) Continuous ink-jet printing uses a pressurized ink source that produces a continuous stream of ink droplets from a nozzle. The droplets of ink are directed either thermally or by electrostatic means at a nominally constant distance from the nozzle. Those droplets which are not successfully deflected are recycled to the ink reservoir via a gutter. ii) Drop-on-demand ink-jet printing where the ink is stored in a cartridge and fired from the print-head nozzle using a pressurization actuator (usually thermal or piezoelectric). With drop-on-demand printing only the drops that are required for printing are produced. iii) Single pass ink-jet printing where the ink is fired by a print-head with hundreds and in some cases thousands of nozzles arranged at a high density on a face plate (also known as a nozzle plate) during a single-pass of the print-head over the substrate. These print-heads are used in industry where a high volume throughput is required. Single-pass print-heads may rely on ink being fed directly to the print-head from an ink storage container or they may be an ink re-circulating single-pass print-head. In ink re-circulating single-pass print-heads the ink is continuously re-circulated in the print-head and (as in drop-on demand printing) only drops required for printing are drawn off to the nozzle.

#Each of these types of ink-jet printing presents unique challenges. Thus, in continuous ink-jet printing ink active solvent monitoring and regulation is required to counter solvent evaporation during the time of flight of droplets which are ejected from the nozzle, but which do not give rise to a printed image (i.e. the time between nozzle ejection and gutter recycling), and from the venting process whereby excess air (drawn into the reservoir when recycling unused drops) is removed.

#The self-dispersible pigment used were Pro-Jet® APD 4000 Black (K) (Carbon Black) and Pro-Jet® APD 4000 Magenta (M) (Pigment Red 122). The Pro-Jet® APD 4000 pigment dispersions are available from FUJIFILM Imaging Colorants Limited.

#Surfynol® 440 is an acetylenic surfactant from Air Products.

#Rovene® 4170 is a styrene butadiene dispersion from Mallard Creek Polymers. The Tg of Rovene 4170 is 4° C. and the acid number is 50mgKOH/g.