The effect of the structure of three-layer polyelectrolyte coatings on the interaction with a water-based inkjet ink comprising dye colorants was determined. Various combinations of anionic–cationic polyelectrolyte structures were prepared on base paper having different hydrophobicity obtained by varying dosages of an alkyl succinic anhydride (ASA) internal sizing agent. Thin coating layers of anionic NaCMC and/or cationic PDADMAC were alternately wet-on-wet spray-coated onto the substrates. It was found that the level of internal sizing affected the spreading and absorption of dye-based inkjet ink, but that the behavior was strongly dependent on the chemistry and structural composition of the deposited polyelectrolyte layer. Polyelectrolyte surface treatment had an effect on the print quality and, e.g., the print density could be improved with cationic surface treatment but also with increasing level of internal sizing. A significant difference in the water fastness of the printed samples was seen, which could be ascribed to the influence of complexes formed between anionic and cationic polyelectrolytes and to their interactions with ink colorants.

The effect of the structure design of a polyelectrolyte cationic and anionic multilayer coating on the liquid– and ink–substrate interaction was studied. The layered structures of anionic–cationic coatings were systematically changed and studied in order to clarify the effect of the polyelectrolyte complexes on the interaction with water-based pigmented inkjet inks. In addition, various amounts of an alkyl succinic anhydride (ASA) were used to increase the hydrophobicity of the base paper before triple deposition of anionic polyelectrolyte (NaCMC) and/or cationic polyelectrolyte (PDADMAC). The coatings were wet-on-wet spray-coated onto the substrates to form various three-layered structures. The results show that the order of deposition of the polyelectrolytes and the ratio between cationic and anionic polyelectrolytes have a significant effect on the print quality. The role of substrate hydrophobicity for the three-layered structure obviously showed that it affected the spreading and wetting behavior of the deposited polyelectrolyte coatings, and subsequently the print quality. The composition of the anionic–cationic polyelectrolyte coatings had a strong influence on the spreading and adhesion of pigmented water-based inkjet inks. The influences of polyelectrolyte structures and composition were more obvious and differentiated when applying on the hydrophilic substrate, revealing the role of ink absorption behavior.

We study the color reproduction of full-color metallic-ink images. Full-color metallic-ink images are prints whose contributing colorants are exclusively made of colored metallic inks. Due to the presence of metallic particles, metallic inks show a metal-like luster. These particles are opaque and hide the underlying ink or substrate. In order to obtain predictable halftone colors, we need a juxtaposed halftoning method to create halftone dots of different colors side by side without overlapping. Juxtaposed halftoning invalidates many assumptions generally made for the color-reproduction workflow. For printing metallic-ink images, one needs a color-separation system creating surface coverages for the eight metallic inks that correspond to the eight Neugebauer primaries. For this purpose, we introduce a simple and fast method for N-color separation that relies either on Demichel’s or on a variant of Kueppers’ ink-to-colorant separations. Thanks to a unique set of ink-to-colorant formulas, pseudo-CMY ink values are separated into amounts of printable colorants. We also describe color-separation procedures that are able to optimize different properties of the resulting metallic-ink images.

The first photographic imaging process was introduced to the world by Louis-Jacques-Mandé Daguerre in Paris in 1839. This unique photographic system has been studied using two-dimensional (2D) and three-dimensional (3D) focused ion beam scanning electron microscopy (FIB-SEM) and transmission electron microscopy (TEM) to probe both historic 19th century and modern daguerreotypes. The electron microscopy images elucidate the process of image particle formation on the silver surface as a light-induced silver reduction initial step followed by a critical two-step silver mercury amalgam crystal development process. The first development step involves the chemical interaction between the gaseous mercury and the surface latent image silver clusters to form the initial amalgam seed image particle. The second development step continues to grow the initial amalgam seed to become a larger image particle able to scatter light. The initial silver and mercury amalgam seed image particle grows further through the amalgamation process. This continued growth involves the reaction of gaseous mercury and silver at the interface between the seed image particle and the silver surface, and silver from the sub/meso-surface that has migrated to the surface via atomic/mass transfer.

This review traces the history and development of organic photoconductors (OPCs), the multilayer thin film photosensitive element in electrophotographic printers, from Chester Carlson’s 1938 demonstration of xerography to the present. A brief discussion of the history of electrophotography is followed by a review of OPC basics and the development of specific charge generating materials (CGMs) and charge transporting materials (CTMs). Next is a discussion of OPC commercialization and the last section demonstrates the cycle of OPC research and development by the number of OPC presentations at international conferences.

Although electrophotography has matured in recent years, there are still some advanced developments in progress—mainly in Japanese companies—to achieve high-quality color printing at a quality similar to or better than that of offset printing, high-speed printing for large-volume commercial printing, and to enhance environmental suitability and usability by utilizing information devices and technologies. In this article, the technologies and advancements in development in the past five years are reviewed with respect to the electrophotography process, key materials—toner and photoreceptor, image processing, environmental suitability and usability. Some new and remarkable commercialized products and spin-off technologies of electrophotography are also introduced in this article.