Pigmented ink jet inks have become increasingly popular as the stability, reliability and performance of these materials has improved to an extent that they are enjoying widespread used in most desktop printers. The traditional method of achieving this level of reliability is to ensure the pigment particle size is as small and as uniform as possible to help eliminate settling and clogging of the nozzles.In contrast, this paper discusses methods of reliably jetting pigments with particle sizes and densities in opposition to the current trends of decreasing pigment particle size. In particular, we discuss the use of specific tailored dispersion chemistries in combination with bespoke ink supply systems in order to jet pigments with densities of up to 10 g/cm3 and mean particle sizes of 5 microns and beyond.Results demonstrate that the traditional approach to dispersing pigments is no longer valid when dealing with these “difficult” materials and that settling is unavoidable and so must be characterised and manipulated through the ink chemistry.
Philip Bentley, "Reliable Jetting of Difficult Materials" in Proc. IS&T Int'l Conf. on Digital Printing Technologies (NIP20), 2004, pp 773 - 773, https://doi.org/10.2352/ISSN.2169-4451.2004.20.1.art00054_2