Formulation, Quality, Cleaning, and Other Advances in Inkjet Printing

Abstract

This article describes a series of modern developments carried out by the inkjet community in its quest to improve material compatibility, printing quality, and reliability. Recent progresses in rheology have advanced our understanding of liquids at the time scales that are characteristic of inkjet printing processes. As a result, microsecond rheology now permits the formulation of inks with tailored viscosities that vary according to the time-scale of their dynamics, i.e. low effective viscosity during jetting but high at break up and landing. These advances have permitted the community to assess, and often predict, the ink jetting behaviour, at a given printing frequency, based on the linear or non-linear viscoelasticity and other fluid characteristics. Advances in fluidic systems and in waveform design have now enabled the printing of high viscous inks that were previously impossible to jet on demand. This capability is opening up new markets and opportunities for inkjet, from the printing of glues to the use of heavily loaded ceramic inks. Advances in printhead design, and the assessment of printing patterns using common standards, now allow the verifiable and reliable operation of industrial-scale digital inkjet printing in a wide range of environments. Recent improvements on printhead cleaning protocols, have contributed to an increase in printing speed and operating time by reducing the production of mist and satellite droplets neighbouring the printhead region. Thanks to these improvements, inkjet is displacing traditional technologies, such as offset and screen printing, in large markets including graphics, packaging and labelling.

Inkjet-Printed Dielectric Layer for the Enhancement of Electrowetting Display Devices

“…The impact of fluidic properties alongside variables such as nozzle diameter on the material’s “jettability” can be efficiently assessed by employing dimensionless numbers, including the Reynolds (Re), Weber (We), and Ohnesorge (Oh) numbers [ 37 ]. The Reynolds number, delineating the ratio between inertial and viscous forces, is defined as: …”

Inkjet printing quality improvement research progress: A review

“…There are two common cleaning methods for print heads: contact and non-contact. Non-contact cleaning typically involves suctioning or extracting impurities from the print head, while contact cleaning is done by wiping with a roller along the print head [ 71 ]. Yang Guiyong et al invented an ultrasonic cleaning system for ceramic printer heads [ 72 ].…”

Fragmentation of colliding liquid rims

“…Liquid atomisation is a class of challenging multiphase problems (Obenauf & Sojka 2021) featuring a large separation of scales and various interacting physical mechanisms, and is of significance to numerous fields of application including meteorology (Villermaux & Bossa 2009), ink-jet printing (Castrejón-Pita et al. 2015, 2021; Lohse 2022), internal combustion engines (Yarin 2006) and pharmaceutical manufacturing (Mehta et al. 2017).…”