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Digital printing is affected by several parameters therefore, Process changes aimed at improving printer engine performance must take into consideration not only the process variables, but also the melt rheological variables. The thermo-mechanical properties of Konica Minolta BizHub C350 toners (in four colors) have been investigated with TGA, DSC and rheometer, as well as the physical and optical properties that have been evaluated using optical microscope, laser scattering particle size analyzer and spectrophotometer. The thermo-rheological evolution of the electrophotographic printing toners in the fusing stage of the image development has been investigated thoroughly. It was found that by increasing the temperature, the toner particles undergo initial surface fusing at around 70 °C which is followed by reduction in viscosity. However, the melting of the particles takes place at 155-172 °C which is resulted in completely merged particles. The melting temperature of the fur colors are occurred at a specific order that matches the standard printing sequence of four-color printing. [ABSTRACT FROM AUTHOR]

Wet-on-wet printing is frequently used in inkjet printing for graphical and industrial applications, where substrates can be coated with a thin liquid film prior to ink drop deposition. Two drops placed close together are expected to interact via deformations of the thin viscous film, but the nature of these capillary interactions is unknown. Here, we show that the interaction can be attractive or repulsive depending on the distance separating the two drops. The distance at which the interaction changes from attraction to repulsion is found to depend on the thickness of the film and increases over time. We reveal the origin of the non-monotonic interactions, which lies in the appearance of a visco-capillary wave on the thin film induced by the drops. Using the thin-film equation, we identify the scaling law for the spreading of the waves and demonstrate that this governs the range over which the interaction is observed. [ABSTRACT FROM AUTHOR]

In printing, the most important element is to obtain the correct substrate and ink combination. Transparent white and opaque white are used for the lightening of printing inks, but they are also an important component for the mixing of inks. The primary objective of this study was to assess the result of using transparent and opaque white in mineral oil-based offset printing inks on the rheological and printability properties of these inks as well as the ideal mixing ratios in terms of print quality. Transparent and opaque white were added into the standard offset magenta ink variable ratios. Differences in ink viscosity, tack, and flow (rheological) values affect such parameters as adhesion, transferability, and printing stability in these inks. Prints were made on matt-coated papers of the same grammage with these inks, and contact angle, solid ink density, color strength, and print gloss values of these ink films were measured. Color differences () of inks in comparison to the standard ink were calculated and the effects of transparent and opaque white on the rheological and printability properties of the ink were presented. Finally, the ideal mixture ratios of transparent and opaque white into the ink were determined in terms of print quality and recommendations were presented. [ABSTRACT FROM PUBLISHER]

Three-dimensional (3D) bioprinting has become a fast-developing research field in the last few years. Many different technical solutions are available, with extrusion-based printing being the most promising and versatile method. In addition, a variety of biomaterials are already available for 3D printing of live cells. The real challenge, however, remains bioprinting of macroscopic, volumetric constructs of well-defined structures since hydrogels used for cell-embedding must consist of rather soft materials. This article describes recent developments to overcome these limitations that prevent clinical applications of bioprinted human tissues. New approaches include technical solutions such as in situ cross-linking or gelation processes that now can be performed during the bioprinting process, modified bioinks that combine suitable viscosity and cytocompatible gelation mechanisms, and utilization of additional materials to provide mechanical strength to the cell-laden constructs. [ABSTRACT FROM AUTHOR]

This paper introduces a pneumatically driven inkjet printing system that forms highly viscous microdroplets in the nanoliter volume range. The printing system has a unique printing mechanism that uses a flexible membrane and an effective backflow stopper. While typical inkjet systems can handle liquids with a limited range of viscosity due to energy loss by viscous dissipation at the nozzle and ineffective backflow management within their systems, our printing system can print liquids with viscosity as high as 384.5 cP. In the viscosity range 1-384.5 cP, we investigated printing characteristics such as printed droplet volume, standoff distance, and maximum possible frequency. The droplet formation showed outstanding reliability, with the droplet volume exhibiting a coefficient of variation less than 1.07 %. Our printing system can be directly used in inkjet applications with functional liquids over a broad viscosity range. [ABSTRACT FROM AUTHOR]

Highly scaled direct gravure is apromising printing techniquefor printed electronics due to its large throughput, high resolution,and simplicity. Gravure can print features in the single micron rangeat printing speeds of ∼1 m/s by using an optimized cell geometryand optimized printing conditions. The filling of the cells on thegravure cylinder is a critical process, since the amount of ink inthe cells strongly impacts printed feature size and quality. Therefore,an understanding of cell filling is crucial to make highly scaledgravure printed electronics viable. In this work we report a novelexperimental setup to investigate the filling process in real time,coupled with numerical simulations to gain insight into the experimentalobservations. By varying viscosity and filling speed, we ensure thatthe dimensionless capillary number is a good indicator of fillingregime in real gravure printing. In addition, we also examine theeffect of cell size on filling as this is important for increasingprinting resolution. In the light of experimental and simulation results,we are able to rationalize the dominant failure in the filling process,i.e., air entrapment, which is caused by contact line pinning andinterface deformation over the cell opening. [ABSTRACT FROM AUTHOR]

This article describes the process of relief image forming by UV-varnishes on self-adhesive labels done by means of screen printing plates with different screen mesh - 36 and 90 lines per cm. The influence of substrates' surface energy on the process of UV-varnish transfer has been investigated. It was defined a disproportional distribution of surface energy on nonprinted self-adhesive paper and it was determined the influence of screen ruling on the varnishing relief's height as well as the value of substrate's surface energy and viscosity of UV- varnish. [ABSTRACT FROM AUTHOR]

Abstract: In this paper we report about some aspects and the progress reached in the reel-to-reel (R2R) solvent-based production of polymer solar cells. In awareness of the huge advantages in energy and material savings the hole-injection and the photoactive layer were successfully prepared by continuous slot-die wet coating of low viscosity inks. The objective was to obtain higher values of light power conversion efficiencies for reducing the gap between production under optimal laboratory conditions via spin-coating on rigid substrates in comparison to the more robust and practically significant large-scale coating of flexible substrates. For this purpose, solvent systems were varied and a new fullerene used as electron–acceptor, leading to the highest light power conversion efficiencies (η=4.55%) described for polymer solar cells (PSCs) on flexible substrates up to now. PSCs manufactured from continuously coated foils by using a small-scale laboratory R2R-coating machine yield a maximum value of η=3.2%. With respect to environmental, safety and technological demands, reel-to-reel wet coating with a change to non-halogenated inks was also successfully carried out in order to learn more about its technological suitability and to allow the transfer of the results afterwards to other, more efficient material systems. [Copyright &y& Elsevier]

Abstract: Biofabrication of three dimensional tissues by Laser-Assisted Bioprinting (LAB) implies to develop specific strategies for assembling the extracellular matrix (ECM) and cells. Possible strategies consist in (i) printing cells onto or in the depth of ECM layer and/or (ii) printing bioinks containing both cells and ECM-like printable biomaterial. The aim of this article was to evaluate combinatorial effects of laser pulse energy, ECM thickness and viscosity of the bioink on cell viability. A LAB workstation was used to print Ea.hy926 endothelial cells onto a quartz substrate covered with a film of ECM mimicking Matrigel™. Hence, effect of laser energy, Matrigel™ film thickness and bioink viscosity was addressed for different experimental conditions (8–24μJ, 20–100μm and 40–110mPas, respectively). Cell viability was assessed by live/dead assay performed 24h post-printing. Results show that increasing the laser energy tends to augment the cell mortality while increasing the thickness of the Matrigel™ film and the viscosity of the bioink support cell viability. Hence, critical printing parameters influencing high cell viability have been related to the cell landing conditions and more specifically to the intensity of the cell impacts occurring at the air–ECM interface and at the ECM–glass interface. [Copyright &y& Elsevier]

Abstract: The inks used in gravure–offset printing are non-Newtonian fluids with higher viscosities and lower surface tensions than Newtonian fluids. This paper examines the transfer of a non-Newtonian ink between a flat plate and a groove when the plate is moved upward with a constant velocity while the groove is held fixed. Numerical simulations were carried out with the Carreau model to explore the behavior of this non-Newtonian ink in gravure–offset printing. The volume of fluid (VOF) method was implemented to capture the interface during the ink transfer process. The effects of varying the contact angle of the ink on the flat plate and groove walls and geometrical parameters such as the groove angle and the groove depth on the breakup time of the liquid filament that forms between the plate and the groove and the ink transfer ratio were determined. Our results indicate that increasing the groove contact angle and decreasing the flat plate contact angle enhance the ink transfer ratio and the breakup time. However, increasing the groove depth and the groove angle decreases the transfer ratio and the breakup time. By optimizing these parameters, it is possible to achieve an ink transfer from the groove to the flat plate of approximately 92%. Moreover, the initial width and the vertical velocity of the neck of the ink filament have significant influences on the ink transfer ratio and the breakup time. [ABSTRACT FROM AUTHOR]

Fine calcium carbonate is frequently used as coating pigment, e.g. in paints, paper and board. Emulsion polymer latex provides a typical binder incorporated in such coatings. Exposure of the resulting porous structure to liquid, depending on latex concentration level, results in ab- and adsorption as the liquid is drawn into the structure by capillarity and the nature of the relative surface chemistry of the pores. Previous work has shown that typical coating structures act to separate oil components according to their surface energy characteristics and solubility index in respect to pigment surface and intra-latex diffusion. This study considers water and alkane (hexadecane) as model liquids. Absorption rate into compressed tablets of ground calcium carbonate is observed with and without the presence of latex. Polyacrylate dispersant used in manufacture renders the pigment surface both hydrophilic and hygroscopic and, therefore, controls the differential dynamic wetting characteristics of the porous structure for either polar or non-polar liquid. In competition with hexadecane saturating the pore structure of a latex-free sample, polar water is seen to displace the non-polar liquid instantaneously, causing disintegration of the packed porous structure. In the presence of latex binder, however, the structurally destructive pressure this creates is contained, and retardation of the polar water is observed. The required pre-wetting action of water vapour diffusion on the polyacrylate pigment surface is considered to be an integral part of the successful competition between oil and water in the offset printing process, as non-polar oil absorbs steadily into a water pre-saturated structure. [ABSTRACT FROM AUTHOR]

The aim of this study was to reveal the feasibility of adjusting aqueous nonoxide ceramic inks for producing complex-shaped functional ceramic parts by direct inkjet printing using the example of silicon nitride (Si3N4) and molybdenum disilicide (MoSi2). In a first step, aqueous Si3N4 and MoSi2 suspensions with high solid contents were prepared by the addition of organic and inorganic additives to meet the requirements regarding rheological properties of the printing system. For this purpose, viscosity, zeta potential, and surface tension were adjusted. Because of the physical conditions of the printing head, the particle size distribution of the suspensions was optimized. The experiments were verified by calculating the Ohnesorge number of suspensions. The results show that the values fit well into the required range. Printing of 3D-components and Si3N4/MoSi2 multilayers was carried out. Optimal performance and control of the printing process resulted in fabrication of homogeneous green bodies without delaminations or other process-dependent defects. [ABSTRACT FROM AUTHOR]

Resist filling process in UV-nanoimprint lithography is investigated by numerical simulation. A resist droplet on a substrate is pressed by a template and the resist flows laterally with constant velocity. The resist filling processes into the patterned cavity are simulated by various contact angles of template and substrate to the resist. Two kinds of defect modes are observed. A typical defect is induced by branching of the resist flow at the edge of the patterned cavity when the contact angle between the resist and the template is large. The other one is nonfilling into the patterned cavity for low viscosity resist and low contact angle between the resist and substrate, where the resist flows along the substrate and does not flow into the pattern. [ABSTRACT FROM AUTHOR]

Hybrid constructs represent substantial progress in tissue engineering (TE) towards producing implants of a clinically relevant size that recapitulate the structure and multicellular complexity of the native tissue. They are created by interlacing printed scaffolds, sacrificial materials, and cell-laden hydrogels. A suitable biomaterial is a polycaprolactone (PCL); however, due to the higher viscosity of this biopolymer, three-dimensional (3D) printing of PCL is slow, so reducing PCL print times remains a challenge. We investigated parameters, such as nozzle shape and size, carriage speed, and print temperature, to find a tradeoff that speeds up the creation of hybrid constructs of controlled porosity. We performed experiments with conical, cylindrical, and cylindrical shortened nozzles and numerical simulations to infer a more comprehensive understanding of PCL flow rate. We found that conical nozzles are advised as they exhibited the highest shear rate, which increased the flow rate. When working at a low carriage speed, conical nozzles of a small diameter tended to form-flatten filaments and became highly inefficient. However, raising the carriage speed revealed shortcomings because passing specific values created filaments with a heterogeneous diameter. Small nozzles produced scaffolds with thin strands but at long building times. Using large nozzles and a high carriage speed is recommended. Overall, we demonstrated that hybrid constructs with a clinically relevant size could be much more feasible to print when reaching a tradeoff between temperature, nozzle diameter, and speed. [ABSTRACT FROM AUTHOR]

Step-and-flash imprint lithography (S-FIL®) is a promising lithography strategy for semiconductor manufacturing at device nodes below 32 nm. The S-FIL 1:1 pattern transfer technology utilizes a field-by-field ink jet dispense of a low-viscosity liquid resist to fill the relief pattern of the device layer etched into the glass mask. Compared to other sub-40-nmcritical dimension (CD) lithography methods, the resulting high resolution, high throughput through clustering, 3-D patterning capability, low process complexity, and low cost of ownership of S-FIL makes it a widely accepted technology for patterned media as well as a promising mainstream option for future CMOS applications. Preservation of mask cleanliness is essential to avoid the risk of repeated printing of defects. The development of mask cleaning processes capable of removing particles adhered to the mask surface without damaging the mask is critical to meet high-volume manufacturing requirements. We present various methods of residual (cross-linked) resist removal and final imprint mask cleaning. Conventional and nonconventional (acid-free) methods of particle removal are compared and the effect of mask cleaning on pattern damage and CD integrity is also studied. [ABSTRACT FROM AUTHOR]