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The challenge to prevent the counterfeiting of documents and the development of flexible printed electronics are two thrust research areas that demand innovative techniques. This study reports the use of fluorene-based Schiff base (FBH) prepared via a simple, one-step and cost-effective method as a thermally stable and biocompatible pigment for environment-friendly, water-based flexographic ink for potential application in security printing and flexible printed electronics. The flexo ink coating and print on the UV dull security paper were invisible in the daylight but displayed bluish-green fluorescence under UV light. Moreover, the emission colour of the print was sensitive to changing pH, which further imparted the eco-friendly ink formulation an excellent covert performance that could be exploited for anti-counterfeit application. The functional ink formulation can also be smartly-utilized in stamp/ink pads to obtain invisible fingerprint for detecting forgery. The colorimetric, and densitometry studies, abrasion resistance and surface morphology analysis of both the coated and printed paper samples were also investigated. The electrical measurements of the prints on flexible and low-cost paper substrates with good mechanical properties exhibited high charge carrier mobility with p-type semiconductivity for use in organic printed transistors. This new functional ink could thus be a promising candidate for anti-counterfeiting applications, including food packaging, documents, labels and ink pads, as well as in secure printed electronics.

Developing printed optoelectronic devices based on metal oxide inks requires synthesizing stable suspensions of the desired materials. In this work, pure and manganese doped zinc oxide inks were synthesized by a top-down wet milling route and the role of solvent in ink stabilization and printing was analyzed. Fluid properties of the as-prepared inks were measured and used for studying jettability criteria for inkjet printing. Among the various solvents evaluated, ethylene glycol produced stable oxide inks and satisfied the jetting conditions. The inks were evaluated using a commercial drop-on-demand piezoelectric inkjet printer. The morphology of the patterns printed on glass substrates, for various ink volumes, was investigated and was found to be continuous and showed good optical transmittance. We also investigated the particle segregation in these inks using a custom built direct writing system. This top-down approach, by separating the material development and ink synthesis, can be extended to a variety of metal oxide based inks.

The aim of the work described in this thesis is to characterize the structure of coatings and prints, and to validate models for the optical response and interaction of ink and coating based on optical measurements of physical samples. It is the interactions between the printing ink and the porous structure of the coating layers that are subject to investigation. Experiments have been employed to relate the physical conditions in a flexographic printing nip to the ink setting and the resulting optical response.By comparing simulated and measured results, it was shown that modifications of the surface properties account for the brightness decrease when substrates are calendered. Light scattering simulations, taking into account the surface micro-roughness and the increase in the effective refractive index, showed that surface modifications accounted for most of the observed brightness decrease, whereas the bulk light scattering and light absorption coefficients were not affected by calendering.Ink penetration affects the print density, mottling and dot gain. Results show that ink distribution is strongly affected by surface roughness, differences in pore size and pore size distribution. For samples having different latex amounts and different latex particle sizes, a higher print force did not increase the depth of penetrated ink to any great extent, but rather allowed the wetting to act more efficiently with a more evenly distributed ink film, a higher print density and fewer uncovered areas as a result. Uncovered areas could be linked both to local roughness variations and to local wettability variations on the surface. Samples with different ratios of calcium carbonate/kaolin clay pigment showed an increased porosity and an increase in print density with increasing amount of kaolin in the coating layer.

The last decade has seen a significant increase in research on UV curable digital inks for industrial printing applications with the focus to expand this technique into new markets. However, most of the commercially available inks are based on acrylic monomers, which provide a significant toxicological behavior limiting their applicability in promising fields, e.g. printing on food packaging materials. In this study, a variety of biocompatible monomers based on vinylcarbonate building blocks were evaluated regarding their application in UV curable digital inks. Although, the viscosity and surface tension of these monomers is appropriate for ink-jet printing, the curing speed is far too low for high speed printing processes. In order to circumvent this limitation, thiol-vinylcarbonate formulations were prepared that offer reactivities and double bond conversions (DBC) similar to those of acrylates. For that purpose, a multifunctional thiol was synthesized providing both, low odor and an appropriate low viscosity facilitating the formulation of basic ink-jet inks, which offer excellent jetting behavior, together with good film forming properties and adhesion on PET. Although there are some challenges regarding stability, in particular for pigmented formulations, this system represents a promising alternative to commercially available acrylate based inks.

The ink-jet printing has been widely applied in the decoration of ceramic tiles in last ten years since its excited characteristics provide the possibility to produce the customized ceramic tiles with higher image definition at a lower cost in a shorter duration. The number of ink-jet printers in operation worldwide increased rapidly in recent years. Besides the printer, one of the critical factors for an effective printing is inks. This paper focuses on the ceramic ink and reviews recent development on the preparation of ceramic inks by various methods, such as sol–gel, reverse microemulsion, polyol, hydrothermal and mechanical grinding. Some aspects for future development are proposed based on the application of ceramic inks in industries.

Over the last years many printing ink manufacturers moved toward more sustainable inks. Drivers for this development are besides resource scarcity and a higher legislative burden, an increasing environmental awareness throughout the population and as a result a growing demand for inks with a small ecological foot print. Thus, water-based and UV-curing systems have already started to replace solvent-based inks, which results in a reduction of volatile organic compounds (VOC) released during the printing process. In addition, materials derived from renewable resources, are more frequently used to replace petrochemical ink ingredients, such as polymeric binders, solvents and different additives. These developments often go hand in hand with an economical benefit as these inks allow for reduced drying times and lower equipment cost to name but a few. Nonetheless, many inks are still mainly derived from petrochemical feedstock. This review gives an overview of the developments in the field of printing inks derived from renewable materials, discusses advantages and drawbacks of the systems described and addresses problems unsolved so far.

A novel roll-to-roll flexographic printing process for rechargeable zinc-based battery manufacturing was presented in this paper. Based on the fundamental operating mechanism of flexography, key criteria for developing functional flexographic printing inks were established, including composite ink rheology (steady-state viscosity and yield stress), ink wettability as well as ink dispersing qualities. A variety of MnO2 cathode inks were developed and analyzed comprehensively based on these criteria. A novel type of aqueous cathode ink based on PSBR polymeric binder showed excellent flexographic printability as well as promising electrochemical performance.

With the development of printing technology, greater emphasis has been laid on environmentally friendly materials. Due to its printability and environmental friendliness, Water-based flexo ink is gradually gaining popularity at home and abroad, and has been widely applied in the field of printing. Different from other kinds of bills, scratch-type invoices have an additional scratch area on the surface, which highly covering performance is required for the ink applied. This paper emphatically analyzes and discusses: (a) flexo water-based covering ink and its application in scratch-type invoice covering region printing; (b) how to explore and evaluate new developed green inks. Compared with traditional inks, the water-based flexo ink is free of emissions of volatile organic compounds (VOC), and its popularization might have significant meanings for the environment protection and sustainable development.

This paper analyses the influence of content of printing inks (and different materials used in their production) on work surrounding and the environment, with the special review on eco inks usage. Printing ink presents dispersive system made of number of different components (pigments, vehicle, adhesive materials, aid materials etc.), which all brought together give specific properties suitable for the printing. During production, ink components are put under intensive homogenization and create a paste of specific consistency. Printing inks contain different kinds of organic and inorganic matter, which can be emitted to the air, soil and water, sometimes causing long-lasting damages to the environment. Beside that, toxic and dangerous vapors from inks violate quality of working surrounding and present the threat for employees in printing facilities. Pigment gives color in printing process and presents the most important constituent of the printing ink. Pigment usually contains different heavy metals, while some oils contained in inks, present distillation derivates of crude petroleum and are dangerous substances which might be cancerous. From the aspect of environmental protection, optimal content of printing ink is unavailable to determine, because each printing technique dictates its own demands in printing - quality and printing speed (connected with the properties of ink drying). Thus, the possibility of substitution dangerous substances in printing inks by less dangerous or harmless is limited. Printing process is sensitive to the paper and ink properties, the way of paper production was done and the origin of other repro materials in printing industry. It is the fact that 'eco inks' can't achieve the same results and quality in printing as traditional inks. In that reason, some other measures can be also effective in protecting employees and the environment from the harmful effect of printing inks constituents. Uprising the consciousness of employees and the management of the printeries, conducting of preventive measures and measures for occupational safety present the main moto for socially and environmentally responsible printing business. The highest responsibility in preserving lives and the environment is on the state itself - to implement laws, to concern about their enforcement and to encourige and stimulate printeries to use recycled materials and eco inks.

The Christian Doppler Laboratory (CDL) for Functional and Polymer Based Ink-jet Inks was founded in January 2012 by the Chair of Chemistry of Polymeric Materials (University of Leoben, Austria), together with the DURST Phototechnik DIT GmbH (Lienz, Austria) as industry partner. The research program of the CDL aims at novel concepts for UV curable ink-jet inks, with a strong focus on non-toxic and eco-friendly materials. These new ink-jet inks enable advanced applications in the fields of optics and bio-medicine. For that purpose, alternative radical based curing reactions are explored on a fundamental level to substitute the precarious (meth)acrylate monomers/oligomers in ink formulations. In collaboration with the industry partner DURST, these novel monomers are explored for the realization of conventional ink-jet inks, which are food-proof and can thus be used for the printing on food packaging materials and labels, and also for ink-jet printing on textiles and garments.

Ink transfer and ink penetration into a coated surface, and variations thereof, influences the print density, mottling and dot gain, which affects the achievable print quality and visual appearance ...

The printed materials used for UV-curable inkjet ink have diversity, in order to research the differences of the printability of UV-curable inkjet ink on different printed materials and improve the printing quality of UV-curable inkjet ink printing on different materials, this research select coated paper, glass card adhesive paper, PVC plastic film as printed materials. After printing the same UV-curable inkjet ink,the printing quality indicators of printing proofs including the density of the line, blurriness, raggedness, line width and contrast of printing product lines were tested,and then test the contact angle of UV-curable inkjet ink on three printed materials, combined with wetting situation，analysis the printing quality of UV ink-jet ink on different substrate, prepare UV ink-jet ink with different printability, printing and testing the printing quality, assessing the quality with comprehensive evaluation method. The result shows that it's existed large differences among the printing quality of the same UV-curable inkjet inks printing on different materials. We match the printed materials with the corresponding printability of UV-curable inkjet inks in the practical production, in order to get the best printing results.

Flexographic printing is a process that employs a flexible printing form and low viscous ink, often water-based. The flexible printing form is favourable for printing on rough surfaces, but the high surface tension of the ink may cause printability problems.This work has focused on the interaction between paper/paperboard coating and water-based flexographic ink, aimed at increasing the knowledge about the printing process in form of physical/chemical parameters that are important for ink setting. The effects of printing conditions on print quality, such as printing pressure and temperature, have also been in focus.The work has shown that fluids of different polarities, i.e. different dipole moments, behave differently when being absorbed by a coating layer. Due to their chemical compatibility to the coating layer, fluids with large dipole moment fill the pore matrix of the coating to a lesser extent but penetrate further into the coating than fluids with small dipole moments. On the other hand, polarity of the coating layer also affects the print. When printing on coatings with different polarities, higher print densities was obtained on the more polar substrates. As a tentative explanation, it is proposed that the ink builds different layer structures during drying depending on the coating polarity.Print gloss is related to the ink setting which, in turn, is affected by the solvent retaining capacity of the ink. Large water holding capacity allows the ink components to smoothen out before the structure is set, resulting in a higher print gloss. The rheology of inks is affected by temperature; at a higher temperature the viscosity is reduced. The reduction in ink viscosity at higher temperature has been shown to affect the print quality, e.g., print density and dot gain. It is suggested that a thicker layer is immobilised during impression due to the lower viscosity and that it is an explanation of the higher print density at a higher printing temperature.The influence of impression pressure on dot gain has been experimentally evaluated and mathematically modelled with good agreement. The dot gain is shown to respond non-linearly to the applied printing pressure.Studies based on pilot coated and printed paperboards is also reported, and it is shown that the print quality, e.g. print density, print gloss and dot gain, is largely dependent on the type of ink chosen and on the coating characteristics. Higher clay content in the coating resulted in increased dot gain and a decreased mottling.

UV curing technology has a number of unique advantages over the conventional curing technologies. However, until very recently, there had been few successful examples of the application of UV curing technology in ink‐jet printing. Several reasons, including the requirement of low viscosity for ink‐jet printing inks, were responsible for the lack of development of UV curable ink‐jet printing inks. This paper describes, in some details, the challenges that a formulator had to face in developing UV curable ink‐jet printing inks, together with information on the status quo of UV curable ink‐jet printing technology.

Nano-sized ceramic inks suitable for ink-jet printing have been developed for the four-colours CMYK (cyan, magenta, yellow, black) process. Nano-inks of different pigment composition (Co1–xO, Au0, Ti1–x–ySbxCryO2, CoFe2O4) have been prepared with various solid loadings and their chemico-physical properties (particle size, viscosity, surface tension, ζ-potential) were tailored for the ink-jet application. The pigment particle size is in the 20–80 nm range. All these nano-suspensions are stable for long time (i.e., several months) due to either electrostatic (high ζ-potential values) or steric stabilization mechanisms. Both nanometric size and high stability avoid problems of nozzle clogging from particles agglomeration and settling. Nano-inks have a Newtonian behaviour with relatively low viscosities at room temperature. More concentrated inks fulfil the viscosity requirement of ink-jet applications (i.e., –1 range. The nano-sized inks investigated behave satisfactorily in preliminary printing tests on several unfired industrial ceramic tiles, developing saturated colours in a wide range of firing temperatures (1000–1200 °C).

In Graz, Austria, the European Rotogravure Association (ERA) held a conference where several companies presented new developments in the printing industry including the latest developments in the field of water‐based ink systems. This paper discusses water‐based inks for gravure printing.

Ink-jet printing is becoming a leading technology for traditional ceramics, due to its capacity of reproducing highly resolved and customized images on tile surfaces. Nano-sized inks, produced by the polyol synthesis route, proved to fulfil the printing requirements, tailoring their chemico-physical properties (e.g. viscosity, surface tension) on industrial ink-jet devices, so representing a major breakthrough in the quadrichromy process.

Materials used for the inks in the printing industry is an important material following the paper. The composition of the ink is pigment and organic solvents. However, Ink is used in a variety of chemicals, they are classified as non-green. Therefore, rosin-modified phenolics manufactured by the reaction of phenol and formaldehyde can take the place of eco-phenol free resin and by experiment density, gloss, trapping, contrast and dot gain of printing has been studied as printability. The result of study can support that the properties of printing using eco-phenol free resin such as density, gloss, contrast and trapping is similar to existing ink. In the part of dot gain, the result is excellent. So we were thought to be able to improve some characteristics such as dispersion of black ink, that will be possible for the field applicability.

Hot melt ink jet inks : some new problems needing novel solutionsDerek Wilson and Patrick HaxeilCoates, Electrographics Ltd, Bath EnglandABSTRACTThe fundamental physico-chemical properties of hot melt inks are investigated. Potential problems exist in a numberof key areas if efficient operation and print quality goals are to be achieved. These problem areas are discussed andpractical solutions suggested.1. WHY HOT MELT INK JET?Ink jet printing offers a cost effective means of producing non impact printers for the office and is rapidly becomingthe system of choice for low cost colour. However, one of the main factors limiting the choice of inks is theirenvironmental acceptability. Volatile organic solvents may be used in industrial printing inks, although there we seea move towards more use of water based inks, but they would certainly be unacceptable in the modern office. Thisleaves few choices for the ink maker and the main choice has been to use water as the major component. Waterbased inks bring with them certain limitations, such as their tendency to evaporate at the jet orifice and thereby leavedeposits that block the orifice, but the main drawback is the interdependence of print quality and substrate surface.The surface must be water receptive, limiting the range of media, and even when using paper, the water dropletsspread and migrate along individual paper fibres, leading to poor edge acuity of the printed image. The choice ofcolourants is also limited and water based dyestuffs are normally used.An alternative approach to ink formulation has been known in traditional printing for years and indeed, some fortyyears ago hot melt intaglio inks were being used to give "instant drying" with no solvent loss. High quality imageswere produced on porous or non-porous substrates. More recently this idea has been taken up as a choice for inkjet printers. The basic principle is that the ink is solid at ambient temperatures. The temperature of the ink is thenraised above its melting point and ejected as molten droplets. When the droplets reach the substrate they coolrapidly and retain their shape irrespective of the surface structure of the substrate.2. HOT MELT PROPERTIESIn theory, the hot melt (alternatively called 'phase change') ink requires two components; a binder (or vehicle) anda colourant or range of process colourants. In practice a complex blend of materials may be combined to give thecorrect balance of properties.In order to give stable drop formation the molten ink must have a relatively low viscosity (

The trend towards a greater use of water as the solvent in flexographic and gravure printing inks has been influenced by a number of factors — the growing attention to environmental pollution problems, health and safety aspects, elimination of residual print odour in food packaging printing and conservation of organic solvents.

Electrostatically assisted liquid inks have firmly established themselves as a viable developer option for certain printer applications. In this process a particle, either a pigment or a latex particle, is dispersed and electrostatically charged in a dielectric fluid. Under the influence of an electrostatic field within a development housing the particles undergo electrophoresis to neutralise a latent image that resides on the surface of a dielectric substrate. This results in a hard copy of the latent image being obtained. In this paper we review the properties demanded of a liquid toner, methods of preparing such inks, their colloidal behaviour and their electrical and imaging characteristics. The trade-offs that need to be made when optimising such developers is also discussed. Some conclusions are drawn regarding future materials directions for this toning technology.

In designing ink jet printing devices, the greatest challenge is not in the design of the mechanism nor control aspects of the head. Surprising to many, it is the difficult task associated with the formulation of inks, toners and papers which will give you a suitable image. This image must possess good chromatic and archival characteristics. In the past, inks were the cause of much criticism associated with the bad reputation of ink jet printers; and rightly so. The inks used in ink jet printing were expected to perform many difficult tasks. They were subjected to evaporation and stability tests at high temperatures. They were expected to retain their physical parameters of viscosity, surface tension and pH for months in an oven at 40-60° C. Yet, when they were emitted onto a piece of paper at ambient conditions, they were expected to dry within 3 seconds. Chemists who were formulating inks based on criteria established by mechanical and electrical engineers were at a disadvantage. Inks were not considered a major component to other groups in the development program. Yet inherently, the ink was causing the majority of system failures due to head clogging, component breakdown, etc. The ink chemist was at a distinct disadvantage to begin with. A major cause for orifice clogging was the precipitation of salts out of the dye. Dyes may contain as much as 20 percent salt. A dye with less than 1 percent salt content was not available a few years ago. Today, however, dye manufacturers see the increase of requests for purer dyes and are making them available for a premium. There were not any specialty papers available for ink jet applications. Inks would either sit on the surface of the paper and not dry, or they would cause feathering or bleeding problems. Today there is a variety of papers available for ink jet systems.