Conventional Printing Process Research Articles

Enhanced color density from high-viscosity inkjet inks

AbstractInkjet printing inks are typically limited to low viscosities, employing highly dilute inks with low pigment loading compared with inks for other printing processes. This reduces color intensity, limits productivity, and requires higher drying energy. This study compares standard-viscosity graphic inkjet inks (~13 mPa.s shear viscosity) with higher-viscosity inkjet inks (~60 mPa.s), traditionally considered outside the normal jetting range, for print outcomes on corrugated cardboard with both white coated and brown uncoated liners. Higher-viscosity inks imparted greater color density to the print; this was assessed as being due to both the inherently higher viscosity of the ink reducing penetration into the substrate and the higher pigment loading capable of being contained within these inks. While standard-viscosity inks tended to plateau in color intensity as ink coverage was increased, higher-viscosity inks could increase in intensity throughout the entire coverage range on coated white liner. This effect was dependent on the substrate, with the coated white liner exhibiting up to a 67% increase in maximum color density but the uncoated brown liner showing up to a 13% increase. It is envisaged that wider adoption of higher-viscosity inks can increase both color intensity and printing speed, thus making inkjet more competitive with conventional printing processes.

3D Printing Manufacturing of Lithium Batteries: Prospects and Challenges toward Practical Applications.

The manufacturing and assembly of components within cells have a direct impact on the sample performance. Conventional processes restrict the shapes, dimensions, and structures of the commercially available batteries. 3D printing, a novel manufacturing process for precision and practicality, is expected to revolutionize the lithium battery industry owing to its advantages of customization, mechanization, and intelligence. This technique can be used to effectively construct intricate 3D structures that enhance the designability, integrity, and electrochemical performance of both liquid- and solid-state lithium batteries. In this study, an overview of the development of 3D printing technologies is provided and their suitability for comparison with conventional printing processes is assessed. Various 3D printing technologies applicable to lithium-ion batteries have been systematically introduced, especially more practical composite printing technologies. The practicality, limitations, and optimization of 3D printing are discussed dialectically for various battery modules, including electrodes, electrolytes, and functional architectures. In addition, all-printed batteries are emphatically introduced. Finally, the prospects and challenges of 3D printing in the battery industry are evaluated.

Improved fibre placement in filament-based 3D printing of continuous carbon fibre reinforced thermoplastic composites

This study investigates the mechanism of fibre deposition in conventional 3D printing and presents an aligned fibre deposition (AFD) method to improve the fibre placement. The deposition mechanism reveals that the cracking of the filament in the transition zone and the torsional deformation during the steering path are the main cause of the defects in the conventional printing process. The AFD method is shown to reduce and mitigate the fibre waviness and twisting, hence producing smooth filament deformation, introducing less air voids and fibre breakage during printing. It is found that the AFD method improves the fibre alignment angle from ±25° to ±12° and reduces the void content to 0.27 % during straight-line deposition. During curved-line printing at a large radius of curvature, tow shearing instead of fibre folding is produced by AFD method, resulting in smooth edges with less fibre breakage.

Printing with hydrotalcite hybrid nanoclays and dispersed, reactive, direct dyes

By using nanotechnologies it is possible to colour textile substrates with new printing techniques using dyes that have been discarded from non-exhausted dye baths. Hydrotalcite is clay with a high adsorbent capacity that can be used for the recovery of dyes from textile wastewater. In this work, three different types of dyes will be adsorbed: direct, reactive and dispersed, the first two being anionic and the last one non-ionic. After this adsorption, the aim is to use this clay-dye hybrid to provide colour to a textile printing paste. The results obtained are subjected to colour fastness tests in order to compare them with more conventional printing processes. The hybrids are also analysed by infrared spectroscopy and x-ray diffraction characterisation techniques to check the correct adsorption and formation of the hybrid. Colour measurements are carried out using reflection spectrophotometers to evaluate the colour results of both the hybrids and the printed textiles successfully and also to analyse their TSR. Thermogravimetric analysis carried out on the hybrids allow anticipating the possible results that they may have, they present certain tests of colour fastness to light which are improved thanks to the action of the hydrotalcite.

A comprehensive nano-interpenetrating semiconducting photoresist toward all-photolithography organic electronics.

Owing to high resolution, reliability, and industrial compatibility, all-photolithography is a promising strategy for industrial manufacture of organic electronics. However, it receives limited success due to the absence of a semiconducting photoresist with high patterning resolution, mobility, and performance stability against photolithography solution processes. Here, we develop a comprehensive semiconducting photoresist with nano-interpenetrating structure. After photolithography, nanostructured cross-linking networks interpenetrate with continuous phases of semiconducting polymers, enabling submicrometer patterning accuracy and compact molecular stacking with high thermodynamic stability. The mobility reaches the highest values of photocrosslinkable organic semiconductors and maintains almost 100% after soaking in developer and stripper for 1000 min. Owing to the comprehensive performance, all-photolithography is achieved, which fabricates organic inverters and high-density transistor arrays with densities up to 1.1 × 105 units cm-2 and 1 to 4 orders larger than conventional printing processes, opening up a new approach toward manufacturing highly integrated organic circuits and systems.

(Invited) TheSimultaneous 3D Printing of White and Transparent Gels for Medical Models

Polymer gels containing a large amount of water have biocompatibility and appropriate softness close to living biological tissue. For this reason, many studies focus on how to use the polymer gels in medical field. The generally organ model is made of a silicone resin and is transparent and hard. Therefore, excellent in confirming the position of blood vessels and the like. But it is not suitable for practice or simulation using medical device. So, we aim to develop the gel organ model that overcomes these problems. We developed the desktop type 3D gel printer “RepRap SWIM-ER” which enables three-dimensional(3D) free printing of gels. RepRap SWIM-ER can move a light source at 405nm and form gels in the desired shape by localized photopolymerization. This gel printer irradiates a gel solution layer by layer with UV light. In the conventional printing process of RepRap SWIMER, it was difficult to change the photo polymerization reaction locally because constant speed, scan time and so on. There was also problem that it could use only one gel solution because it was bathtub type 3D gel printer.Here, we developed new printing process of RepRap SWIMER that can change the transparency and mechanical properties of printed gels locally by changing the printing parameters such as the scan times of UV light. It can control gel turbidity which was previously only printed in a single color. This method can print two types of gel (transparent and white) only using RepRap SWIM-ER. By changing the printing conditions with RepRap SWIM-ER, a transparent gel with length and breadth of 20 mm, thickness of 2 mm and a white gel lattice can be printed at about 10 minutes. The transmittances of printed transparent gels and white gels were measured by a spectrophotometer to examine the color change (Figure 1). It can be seen from Fig.1, The white turbidity of the gel changes when the printing conditions are changed. This result showed that the appearance of color varied depending on the concentration of the hydrophobic initiator TPO used in the gel solution.At the prototype, we tried to print using kidney data. From previous research, we have known that the gel prepared by soaking in pure water swells 1.5 to 2.0 times. In consideration of this result, when printing kidney data using RepRap SWIM-ER, it was printed at 70% of the size of the data, the color was entirely white. After swelling, this model became to be about the same size as the actual data. The kidney 70% data can be printed at 2h30min. We can create new gel organ models by using RepRap SWIM-ER and the above gel printing method. Gel organ models makes it possible to use medical devices and makes the touch feeling more realistic. For example, soft-transparent gel (organ model) and hard-white gel (blood vessel, tumor) can make the model with high precision and complexity. In addition, this technology can let the production spend lower cost and less time. Figure 1

Research and implementation of a non-supporting 3D printing method based on 5-axis dynamic slice algorithm

Abstract Conventional three-dimensional (3D) printing technology generates objects and parts layer by layer by depositing material along the Z-axis direction. However, when it comes to overhanging structures in the printing process, the conventional printing process needs the creation of additional supporting structures. So, this technique requires additional materials and increases the effective printing time. To overcome these issues, this paper proposes a novel 5-axis dynamic slicing algorithm to achieve non-supporting material printing (NSMP). The original model is sliced by a series of dynamic planes calculated by the skeleton extraction; the 5-axis printing G-code generated from the sliced layers can control the 5-axis printer to complete NSMP. Finally, a comparison between traditional 3D printing and 5-axis printing is presented to test the utility of this strategy.

Manufacturing of polylactic acid nanocomposite 3D printer filaments for smart textile applications

In this paper, manufacturing of polylactic acid nanocomposite 3D printer filaments was considered for smart textile applications. 3D printing process was applied as a novel process for deposition of nanocomposites on PLA fabrics to introduce more flexible, resourceefficient and cost effective textile functionalization processes than conventional printing process like screen and inkjet printing. The aim is to develop an integrated or tailored production process for smart and functional textiles which avoid unnecessary use of water, energy, chemicals and minimize the waste to improve ecological footprint and productivity.

Investigation of the adhesion properties of direct 3D printing of polymers and nanocomposites on textiles: Effect of FDM printing process parameters

In this paper, 3D printing as a novel printing process was considered for deposition of polymers on synthetic fabrics to introduce more flexible, resource-efficient and cost effective textile functionalization processes than conventional printing process like screen and inkjet printing. The aim is to develop an integrated or tailored production process for smart and functional textiles which avoid unnecessary use of water, energy, chemicals and minimize the waste to improve ecological footprint and productivity. Adhesion of polymer and nanocomposite layers which were 3D printed directly onto the textile fabrics using fused deposition modeling (FDM) technique was investigated. Different variables which may affect the adhesion properties including 3D printing process parameters, fabric type and filler type incorporated in polymer were considered. A rectangular shape according to the peeling standard was designed as 3D computer-aided design (CAD) to find out the effect of the different variables. The polymers were printed in different series of experimental design: nylon on polyamide 66 (PA66) fabrics, polylactic acid (PLA) on PA66 fabric, PLA on PLA fabric, and finally nanosize carbon black/PLA (CB/PLA) and multi-wall carbon nanotubes/PLA (CNT/PLA) nanocomposites on PLA fabrics. The adhesion forces were quantified using the innovative sample preparing method combining with the peeling standard method. Results showed that different variables of 3D printing process like extruder temperature, platform temperature and printing speed can have significant effect on adhesion force of polymers to fabrics while direct 3D printing. A model was proposed specifically for deposition of a commercial 3D printer Nylon filament on PA66 fabrics. In the following, among the printed polymers, PLA and its composites had high adhesion force to PLA fabrics.

Guest Editorial Special Issue on Printable Sensors and Systems

Printing of sensors and electronics has received substantial interest in recent years as the alternative approach to realize low-cost, large-area electronic, optoelectronic and sensing systems. Printed electronics employs conventional printing processes with plastics, papers or textiles as substrates. The adoption of any new technology is significantly higher when the high quality sensor systems are of low-cost. Printed sensors and electronics have clear advantages in terms of production cost and may offer one solution to meet the demand at low cost. For example, the capital expenditure is low; material utilization is high (or material waste is low); the possibility of industrial scale-up is built into the fabrication process. The cost of printed sensors will be 1/10th to 1/100th the cost of the sensor systems made with conventional electronics. With the predicable coming of “Trillion sensors society,” the low-cost manufacturing becomes ever so important. Other factors favoring the use of printing techniques include possibility to tailor the use of different solvent media and hence environmental friendliness. For this reason a significant tool chest of printed sensors and electronics has been built worldwide.

Overlay of semi-dried functional layers in offset printing for rapid and high-precision fabrication of flexible TFTs

We achieved a reduction in the misregistration of overlying patterns printed on a flexible plastic film and a drastically shorter processing time with fully printed thin-film transistor (TFT) fabrication. This was achieved using a newly developed wet-on-wet (WoW) printing process wherein a subsequent layer can be printed on a previous semi-dried (not-sintered) layer. In the WoW process, as examined by rheological measurements, a semi-dried (highly solidified) state of ink was attained before transferring by utilizing the solvent uptake of a PDMS blanket in offset printing to ensure the structural integrity of the ink layer, and to reduce the inter-contamination of adjoining layers. Loss-on-drying tests and resistivity measurements indicated that molecular penetration at the boundary of adjoining layers with a length of c.a. 70 nm occurred in the WoW process; however, with thicker electrodes, we successfully fabricated a WoW-processed TFT whose performance was comparable with a TFT formed by a conventional printing process.

Inkjet printing of single-crystal films

The use of single crystals has been fundamental to the development of semiconductor microelectronics and solid-state science. Whether based on inorganic or organic materials, the devices that show the highest performance rely on single-crystal interfaces, with their nearly perfect translational symmetry and exceptionally high chemical purity. Attention has recently been focused on developing simple ways of producing electronic devices by means of printing technologies. 'Printed electronics' is being explored for the manufacture of large-area and flexible electronic devices by the patterned application of functional inks containing soluble or dispersed semiconducting materials. However, because of the strong self-organizing tendency of the deposited materials, the production of semiconducting thin films of high crystallinity (indispensable for realizing high carrier mobility) may be incompatible with conventional printing processes. Here we develop a method that combines the technique of antisolvent crystallization with inkjet printing to produce organic semiconducting thin films of high crystallinity. Specifically, we show that mixing fine droplets of an antisolvent and a solution of an active semiconducting component within a confined area on an amorphous substrate can trigger the controlled formation of exceptionally uniform single-crystal or polycrystalline thin films that grow at the liquid-air interfaces. Using this approach, we have printed single crystals of the organic semiconductor 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C(8)-BTBT) (ref. 15), yielding thin-film transistors with average carrier mobilities as high as 16.4 cm(2) V(-1) s(-1). This printing technique constitutes a major step towards the use of high-performance single-crystal semiconductor devices for large-area and flexible electronics applications.

Digital Printing: Is It Supplanting Conventional Printing Processes

Digital Printing: Is It Supplanting Conventional Printing Processes

Digital Labels Printing

The HP Indigo press ws4000 is a high-speed, narrow-web digital press that provides cost-effective short- to mediumrun color labels on demand for converters who print labels. With the trend towards fast-turnarounds, higher quality, more colors and shorter runs, label printers, have a real need for the means to improve profitability while meeting these demands. The HP Indigo Press ws4000 offers a complete solution to meet the demands of the Labels printers and the labels users whether it requires special colors, security features, clear or metallic substrates, image changes, numbering, or even personalization. The new HP Indigo Press ws4000 utilizes our Series II engine to deliver up to 105 feet per minute in two colors and 57.5 feet per minute in full color. Unlike conventional printing processes, there are no intermediate pre-press processes between the digital document file and the final print. No film, no image setters, no plates, no platesetters, no photo-chemicals and no waste.There is also no press make-ready: no plate mounting, no registration adjustments, and no ink keys. HP's process is fully digital from creation to printing. And, since it is fully digital, every image can be a new one, enabling information to be completely varied as required. HP's technology uses offset printing, based on the use of an offset cylinder covered with a renewable rubbery blanket. HP Indigo's ws4000 press employs a ‘One-Shot Color’ process, as it is not possible to wrap the material around the impression cylinder for multiple passes. In this case, the PIP cylinder rotates several times, transferring a succession of separations and building them up on the blanket, before they are transferred to the substrate all in the same impression pass. Printing with five, six or seven colors, in addition to CMYK, offers major enhancements in color quality, range, fidelity and luminosity. In summary - HP indigo press ws4000 combines digital, offset, and color into a powerful printing process. HP indigo press ws4000 main value propositions for the labels converter are:• reduce production cost of short- to medium-runs of 35 percent of jobs are under 6500 feet (2000 meters), the ability to run short jobs in a profitable way is essential• faster turnaround time, on-demand (just-in-time principles)• with easy setup• easy and short cleanup• fast change over• ability for last minute changes• no need for films and plates• added-value printing• variable information printing• super print quality• security features• high productivity reflect in quick ROI• end to end solution – printing, finishing and workflow• industrial production – rigid structure, reliable solution and ease of use• ElectoInks - 7 colors printing, white color, spot (corporate colors), IndiChrom, IMS, multi layers printing• substrate flexibility – paper, plastics face stock• little to no waste – first print is the right one