Effect of physical parameters and temperature on the piezo-electric jetting behaviour of UV-curable photochromic inks

Abstract

Although resource-efficient processes like inkjet printing have a large potential to foster the development of smart and functional textiles, one bottleneck still is the development of functional inks. To make inkjet printing and UV curing given production techniques for smart and functional specialty products, e.g. photochromic textiles, deepened knowledge about the development, rheological behavior and jetting behavior of functional ink is needed. This paper focuses on the formulation and performance of UV-responsive and UV-curable inkjet inks, which are based on photochromic dyes and their application to produce UV-responsive textiles. Two commercial photochromic dyes—Reversacol Ruby Red (RR) and Sea Green (SG), which represent dyes of the naphthopyran and spirooxazine class, respectively, have been used to develop the inks. The photochromic inks are characterized according to their physical–chemical and rheological properties in respect to temperature. The influence of temperature on the drop formation of the inks in an industrial print head is analyzed using a high-speed camera, which reveals important information regarding challenges in ink jettability. It was found that the dye structure and type used in the ink can influence the jetting behavior of photochromic UV-curable ink. More pronounced temperature sensitivity of dyes can increase the temperature-related effects of drop formation as was observed for SG ink. The printability of the RR and SG inks is framed and underpinned by theoretical calculations of the Z number. Discrepancies are observed and discussed between existing theory of ink jettability and visual evaluation of the photochromic ink.

Formulation and characterization of pigmented inkjet inks containing aminopropyl/vinyl/silsesquioxane for jet printing onto polyester fabrics

“…It is commendable to specify that the effect of temperature on the surface tension of the ink formulations containing APSV is neglected as of exceptional little changes beyond four cycles. Other than that, the visual examination revealed that the increase in temperature has no thinning effect on the different ink formulations, contrasted to other data recently investigated (Seipel, Yu and Nierstrasz, 2020). Furthermore, the sudden temperature change has not occurred any aggregation of pigment particles in the formulated inks, which is not found to agree with the work reported by Nasar et al (2011).…”