Application Of Inkjet Printing Research Articles

Improvement of UV-curable ink adhesion onto melamine faced board using dual silane treatments

ABSTRACT The application of UV digital inkjet printing onto melamine-faced board (MF) has attracted increasing attention as an efficient and environmentally benign surface decoration method. However, the interface bonding between UV coating and melamine-formaldehyde surface is weak, resulting in poor printing durability. In this study, the MF surface is grafted with 3-(triethoxysilyl) propyl isocyanate (ICPTES) via a urea cross-linking process, and then condensed with γ-methacryloxypropyl trimethoxy silane (KH570) to improve its compatibility with the polyacrylate-based UV ink. A combination of physical (surface polishing) and chemical (dual-silane treatments) activations of MF surface enhances its interface bonding strength with UV coating up to 2.24 MPa, 966.7% and 119.6% higher than those of the untreated and the conventional adhesion promotor treated surface, respectively. FTIR results confirm that effectual chemical bonds are established between MF surface and UV coating by the ICPTES and KH570 dual-silane treatments. SEM imaging shows that a seamless connection between MF and UV coating forms. Thus, MF surface modified by silane is a facile and effective strategy to enhance the adhesion of UV digital ink and this printing method shows enormous potentials in a wide range of applications.

Suppression and Utilization of Satellite Droplets for Inkjet Printing: A Review

Inkjet printing, initially invented for text and pattern printing, has been extensively used to fabricate electronic, mechanical, and even biological devices. Numerous reviews focused on the mechanisms, development, and application of inkjet printing have been published in recent years. However, a small review has focused on the satellite droplets during inkjet printing. Satellite droplets have long been recognized as an undesirable byproduct in the inkjet community since they potentially blur the printing patterns, polluting the printer and the air. Numerous efforts have been made to avoid or suppress the generation of satellite droplets since the inkjet’s birth. However, recent studies demonstrated the delicately utilizing of the satellite for realizing extremely high printing resolution otherwise impossible for the traditional inkjet printing. In this review, we focus on the formation mechanisms of satellites, efforts made to suppress satellites, and techniques developed to utilize satellites, distinguishing them from the existing inkjet printing reviews.

The Driving Waveform Design Method of Power-Law Fluid Piezoelectric Printing Based on Iterative Learning Control.

In some applications of piezoelectric three-dimensional inkjet printing, the materials used are power-law fluids as they are shear thinning. Their time-varying viscosities affect the droplet formation, which is determined by the volume flow rate at the nozzle outlet. To obtain a fine printing effect, it is necessary to present a driving waveform design method that considers the shear-thinning viscosities of materials to control the volume flow rate at the nozzle outlet, which lays the foundation for the single and stable droplet generation during the printing process. In this research, we established the relationship between the driving waveform and the volume flow rate at the nozzle outlet by modifying a model that describes the inkjet mechanism of power-law fluid. The modified model was used to present a driving waveform design method based on iterative learning control. The iterative learning law of the method was designed based on the gradient descent algorithm and demonstrated its convergence. The driving waveform design method was verified to be practical and feasible by implementing drop generation experiments.

On-demand evaporation mode of sessile droplet by designing substrate surface wettability patterns

A conceptual strategy of controlling the evaporation mode of sessile droplet that is demonstrated by the variation of its contact angle and contact radius through designing the surface wettability pattern of substrate is proposed. A theoretical model is established based on the geometry shape of the droplet and minimization of the total surface free energy of the droplet-substrate system. The model is implemented to predict the variation of the surface free energy during evaporation and is used to determine the time evolutions of the contact angle and contact radius. With this theory, a relationship between surface wettability patterns and droplet evaporation modes is established. Comprehensive molecular dynamics simulations are employed to validate the theoretical predictions, and the evolutions of the contact angle and contact radius during evaporation agree well with the theoretical predictions. The proposed technique to control the evaporation mode of sessile droplets is further implemented to control the deposition pattern of nanoparticles by liquid evaporation, which manifests that the theoretical model established herein could explain the underlying mechanism of controlling evaporation mode of sessile droplets and such method of designing substrate surface wettability pattern has potential applications in inkjet printing, nano-assembly, and nano-device manufacturing.

Inkjet-Printed In Situ Structured and Doped Polysilicon on Oxide Junctions

We investigate the inkjet printing of liquid silicon ink to form in situ doped and structured passivating contacts. The ink consists of neopentasilane oligomers in solvents and decomposes into amorphous silicon with a short anneal. By printing boron- and phosphorus-doped ink on silicon oxide, polycrystalline silicon on oxide (POLO) junctions for both p-type and n-type polarities (POLO <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) are formed and the saturation current densities as low as 5 fA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> are achieved for n <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> -POLO junctions. We perform a structured printing in interdigitated back contact (IBC) geometry achieving emitter and base fingers with an average finger height of up to 103 nm. The application of inkjet printing allows for a simplification of POLO and POLO <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> solar cell processing. In particular, for POLO <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> -IBC cells, a lean process flow is facilitated.

Preparation of submicron CdSxSe1-x@ZrSiO4 inclusion pigment and its application in ink-jet printing

A zircon-based inclusion pigment (CdSxSe1-x@ZrSiO4) for ink-jet printing was successfully synthesized by calcining the precursor formed by coprecipitation of Si4+ and Zr4+ on the SiO2 shell of CdSxSe1-x@SiO2 with PAAS as a surfactant. The pigment with cubic or spheroidal morphologies was fully encapsulated within an intact and dense ZrSiO4 shell, and the particle size was concentrated between 500 nm and 800 nm. The intact inclusion structure of the pigment particles was not easily damaged in the grinding stage of ink. The inclusion pigment, which was prepared in the optimum condition of pH value of 7.2 ± 0.2 for coprecipitation, calcination temperature of 900–950 ℃ and soaking time of 30 min, has a high quality of red hue, achieving the chromaticity values of L* = 62.03, a* = 27.35 and b* = 19.64, respectively. The red ink made from this pigment has a good thermal stability and color effect in glazes after calcination at 1210 ℃ for 30 min.

Encapsulation of organic pigment via a facile dispersion approach and soap-free miniemulsion polymerization

Organic pigments are a commonly used colorant with various applications and promising prospects. However, the implement of organic pigments is hindered by poor dispersion stability and unsatisfactory weather resistance. Herein, encapsulated pigments are obtained via a facile dispersion approach and subsequent soap-free miniemulsion polymerization. The reactive emulsifier acting as dispersant and emulsifier in the polymerization integrates advantages of covalent bonding and steric hindrance effect, reducing the residue of excess reagents and improving the stability of pigment dispersion. Due to the interaction between polymers and the dispersants on the pigment surface, as well as the shielding effect of polymer in the core-shell structure, the soap-free nano-pigment composite particles exhibit better dispersion stability, enhanced weather resistance, superior rubbing fastness performance and anti-ultraviolet intrusion ability. In addition, the as-prepared nanocomposite could be applied to flat screen printing, inkjet printing, handwriting and other applications, significantly expanding the practical application value of pigments.

SYNTHESIS OF CONDUCTIVE INK BASED ON SILVER NANOPARTICLES AND ITS APPLICATION IN INKJET PRINTING PATTERNS ON GLASS SUBSTRATES

This paper presents a synthesis of silver nanoparticles-based solution which was then used as conductive ink for inkjet printing application. In this work, colloidal silver nanoparticles (AgNPs) were synthesized from silver nitrate (AgNO3) with polyvinyl pyrrolidone (PVP) as a capping agent and ethylene glycol (EG) as a solvent and reducing agent. After the synthesis, the silver nanoparticle solution was characterized by Ultraviolet-visible (UV-Vis) spectrophotometry Fourier transform infrared (FTIR) method. Transmission electron microscopy (TEM) showed the nanoparticles diameter ranged from 10 nm to 60 nm which is suitable for printing process through the nozzles of the inkjet printhead (the diameter of the printing nozzles was 21.5 µm). After that, some samples with a square shape were printed using this conductive ink on glass substrates which were then heated at different temperatures by a hot plate. The samples were characterized by Field emission-Scanning electron microscopy (FE-SEM) and a non-contact surface charge analyzer. It was found that with the heat-treatment from 200oC to 250oC the printed samples obtained the resistivity of 0.4-0.5 Ω, which could be used for electronic applications

Microfluidic synthesis of CsPbBr3/Cs4PbBr6 nanocrystals for inkjet printing of mini-LEDs

Zero-dimensional Cs4PbX6 (X = Cl, Br, I) perovskite material is recognized as a potential luminescent material and host owing to its excellent optical properties. However, the synthesis of large-scale CsPbBr3/Cs4PbBr6 complex nanocrystals (NCs) is difficult, and their application in mini- or micro-LEDs remains limited. Herein, we applied a microfluidic system for a simple, continuous, and stable synthesis of CsPbBr3/Cs4PbBr6 NCs. The CsPbBr3/Cs4PbBr6 complex NCs were obtained after the optimization of the Cs/Pb precursor ratio and alkaline environment, and their photoluminescent quantum yield is up to 86.9%. These as-synthesized CsPbBr3/Cs4PbBr6 NCs were used to produce a luminescent ink with the optimization of different solvents. This ink was successfully used to print large and high-resolution patterns, and fabricated mini-sized color-converted LED. The narrow green emission of the LED well obeyed the requirements of the Rec. 2020 standard, demonstrating the potential of this material in the inkjet printing applications of color-converted mini- or micro-LED arrays.

Preview the Products on Display at Display Week 2021

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Recycling of steelmaking electric arc furnace dust into aqueous cyan ceramic ink for inkjet printing process and its printability

Recycling of electric arc furnace dust (EAFD) has great potential for industrial applications, due to its useful metal contents, including zinc. In this study, aqueous cyan ceramic ink for ink-jet printing applications was synthesized using EAFD. More specifically, cyan ceramic pigments were synthesized using an empirical composition of Zn(EAFD)XCo1-XAl2O4, in which expensive cobalt oxide is replaced by Zn-enriched EAFD. Zn(EAFD)0.25Co0.75Al2O4, which has a vivid cyan color, was selected as the optimum composition of cyan ceramic pigments for synthesizing aqueous cyan ceramic ink for ink-jet printing applications. To prevent nozzle clogging during ink-jet printing, the cyan ceramic pigments were micronized. The micronized pigments were mixed with distilled water and dispersant to fabricate aqueous cyan ceramic ink. To determine the optimized jettability and printability of this ink, its rheological properties, including viscosity and surface tension, were adjusted and analyzed. It was concluded that the jettability and printability of aqueous cyan ceramic ink produced via ink-jet printing could be enhanced by appropriately adjusting its viscosity.

Application of inkjet printing in the large area display of organic light-emitting diode

<p indent=0mm>As the interaction media between human beings and electronic devices, display technology has become more and more important in our daily life with the development of modern information technology such as big data technology and artificial intelligence, which also brings the huge demands on the market of large area display. Active organic light-emitting diode (OLED) is one of the most competitive candidates for the next-generation display, fulfilling the demand of vivid color, wide view angle, flexible stretchability and high contrast. Thus, OLED devices have already been widely applied in small-size displays such as smart watches, smart phones, tablet computers and automobile monitor and so on. However, currently most commercialized OLED devices are still fabricated by high-cost methods, greatly hindering their application in large area display. For example, in the commercial large area display, only white OLED technology has been practically employed regardless of its high fabrication cost which is the reason of its less sharing market occupancy. White OLED technique faces some difficulties that can hardly be solved perfectly for adopting thermal deposition process, such as poor utilization of organic materials, expensive deposition facilities and low product yields, etc. The technique of QD-OLED is another alternative method for large area display, which is the upcoming scheme Samsung promotes firmly, but it has been repeatedly delayed in the mass production because there are still some unconquered barriers in materials and manufacturing processes. According to the announcement of Samsung display company, in the next half year of 2021, the commodity of QD-OLED will be appeared finally, but it could not be sold in large quantities, which will be with high price exceeding expectation of consumer. Therefore, including TV, phone and monitor, the retail price of OLED products is much higher than that of liquid crystal display (LCD) all the time, impeding the commercial application of large area OLED. With the advantages of effective material utilization, low cost and convenient fabrication of large area panel, inkjet printing is relatively suitable for the manufacture of large area OLED display, which is the crucial developing technique to the display companies and researching institutes. Except the immaturity of industrial inkjet machine and process, the efficiency and stability of OLED based on inkjet printing can’t satisfy the requirements of commercialized application. Consequently, it is significant that OLED based on inkjet printing with high efficiency and long lifetime is realized and marketed by improving ink materials, devices and processes to achieve low price and outstanding performance. In this paper, starting with descripting the current status of large area OLED display, we briefly introduce the recent progresses of inkjet printing OLED and relevant materials and devices, as well as their applications in large area display. Finally, we present our ideas about the future developing direction of new display of OLED based on inkjet printing technology.

Inkjet printing of phosphorus dopant sources for doping poly-silicon in solar cells with passivating contacts

In this work application of inkjet printing of phosphorus inks as dopant source for fabrication of silicon solar cells with tunnel oxide passivating contacts (TOPCon) was demonstrated. Inkjet printing is of great importance for the formation of selectively doped TOPCon layers of industrial TOPCon cells to provide a low contact resistance, while creating the requirements for screen printing metallization. Rheological characterizations were carried out in order to determine the complex viscosity and elastic effects of the inks. Printing processes were developed and optimized accordingly, given the significant relevance of rheology in inkjet printing. It was realized that inkjet printing processes have a direct influence on the electrical properties of passivating contacts. Droplets with a diameter of below 35 μm and lines with sharp edges and width of down to 70 μm were obtained. Excellent passivation quality was achieved for inkjet-printed n-type poly-Si surfaces with an implied open-circuit voltage of iVoc = 733 mV and an implied fill factor of iFF = 86.4%. For n-type passivating contacts, doped by inks containing phosphorus, the junction characteristics were investigated using double-sided contacted silicon solar cells. With these cells, Voc = 703 mV, FF = 72 %, and conversion efficiency of η = 17.1 % were realized. For ion-implanted poly-Si surfaces, herein used as reference, η = 18.2 % was obtained, underlining the high potential of investigated inkjet printing processes.

A Study on Colour Print Quality Attributes Variance of OMR between PET and ABS by Digital Inkjet Printing

In-mould transfer printings are limited, such as surface bending, only on plastic parts, cost higher and print for a small run length of productions. OMR transfer can be transferred to plastic or metal, transfer process accurate register, high quality and tolerance. The current printing market tend to develop personalized, so this study to use digital inkjet printing, through rigorous experimental process and quantitative measurement and comprehensive analysis, summarized the most suitable digital inkjet printing methods and the best quality attributes. In each combination, the samples will be selected to transfer printed products which will be examined for print quality attributes (SID, TVI, PC, colour difference and colour gamut). This study results found that when the higher coverage and the lower pass of inkjet printing, the SIDs will become higher as well. When transferred to ABS, SIDs in each combination will increase. The higher coverage printed, the higher TVI. After transferred into ABS, each combination of PC is worst. When transferred to ABS, colour variances of each combination are different from orange and cyan colour. Through this study, we can get the colour correspondence between the original and the finished product ABS, to establish the personalized service process, to improve the digital inkjet printing and technology application to enhance its product added value, and to provide research results to give back to the printing market. It can bring new opportunities for the industry.

Drying stability enhancement of red-perovskite colloidal ink via ligand-derived coating for inkjet printing

Today, inkjet printing techniques has many merits such as high printing yield and mask-free process for the various field. As one of the candidate ink materials, the perovskite is appropriate for inkjet printing due to the colloidal state and excellent optoelectronic properties such as high photoluminescence quantum yield (PLQY) and narrow full width at half maximum (FWHM). Those characteristics are an advantage to fabricating ink and realize wide color-gamut in the small area with micro-patterning. However, perovskite application in inkjet printing with various color has limitations due to the low drying stability of mixed halide perovskite.Herein, we report on improving the drying stability of red perovskite by inducing aggregation during the drying process. Silane ligand has applied to induce the aggregation, and we confirmed that the thin coating layer has formed on the perovskite surface. The synthesized red-perovskite using silane ligands is well dispersed in the solvent as a colloidal state. And it maintained the emission intensity over 50% after drying. As-prepared perovskite ink has successfully printed on the ethyl cellulose film with 338 dpi with maintaining transparency of the film. These results are beneficial not only display applications but also security applications such as double anti-counterfeiting.

Drying behavior of magnetic nanofluid in ambient conditions

The study of evaporation patterns of liquid drops is a growing field of research with numerous applications in inkjet printing, controlled particle deposition, self-assembly, etc. After the liquid in a drop completely evaporates, it leaves behind the constituent particles in various patterns on the substrate. This depends on factors such as ambient temperature, substrate’s thermal conductivity, particle size, and density. Ferrofluids are known to show a variety of magnetic field dependent properties. Controllable evaporation using ferrofluids can result in desired patterns of particles on a substrate. However, before studying the evaporation of these nanofluids in the presence of magnetic field, their drying behavior under ambient conditions needs to be studied. Here, kerosene-based ferrofluid droplets were allowed to evaporate under ambient conditions. Video analysis of particle motion showed a Marangoni flow inside the drop. At the early stages of evaporation, non-interacting Marangoni instability loops were observed with equidistant empty lines between them propagating in the radial direction. These lines merged in the later stages of evaporation. The particles moved from the center toward the contact line and reversed their direction at a very close distance from the contact line, moving toward the top of the drop through the liquid–air interface. The distance of the point of reverse motion, called the stagnation point, was measured from the contact line, and it agrees with an existing theory. Moreover, the measurements of contact angle and mass evolution indicate that this evaporation follows the model of thin droplets. After drying, the ring pattern was observed on the substrate with a central accumulation of particles. The region between the central accumulation and the outer ring was seen to be empty. The size of this empty region decreased with increasing droplet size and increasing volume fraction of the nanoparticles. This study may help in understanding the drying behavior of magnetic nanofluids under ambient conditions for self-assembly and inkjet printing applications. The drying behavior in the presence of external magnetic field will be discussed in the future.

Spreading and retraction kinetics for impact of nanodroplets on hydrophobic surfaces

Impact dynamics of nanodroplets has recently gained extensive attention because of its potential applications in nanoscale inkjet printing, nanodroplet spray cooling, and nanocoating. In this study, a nanodroplet impacting unheated, flat, smooth, and hydrophobic surfaces is investigated via molecular dynamics simulations. The emphasis is placed on spreading and retraction kinetics, i.e., time-dependent wetting radius or r–τ relation, where r and τ are the normalized wetting radius and time. On the basis of an energy conservation approach, an analytical model of r–τ kinetics is developed for impacting nanodroplets. Hypotheses of cylinder droplet and extensional flow are employed to calculate the transient kinetic energy and viscous dissipation rate, which are found to be the most appropriate for impacting nanodroplets. The model is tested in a range of Weber numbers from We = 15 to 60, Reynolds numbers from Re = 11.07 to 22.19, and surface wettability θ0 = 105° and 125°. The tests show that the mean relative deviation ranges from 2.22% to 5.47%, and hence, the developed model captures the spreading and retraction kinetics of a nanodroplet impacting hydrophobic surfaces with satisfactory accuracy. Furthermore, it is found that the model can also be extended to predict the retraction kinetics of nanodroplets on hydrophilic surfaces for high Weber numbers.

Rheological properties of carboxymethyl hydroxypropyl cellulose and its application in high quality reactive dye inkjet printing on wool fabrics

In this paper, the effect of rheological properties of pretreatment solutions, using carboxymethyl hydroxypropyl cellulose (CMHPC), sodium carboxymethyl cellulose (CMC), and sodium alginate (SA) as thickeners, on inkjet printing performance of wool with reactive dye inks was examined. Rheological, FESEM, and thickness results showed that fabrics treated with CMHPC solution, which exhibited superior fluidity, dominant elasticity property, and the largest zero-shear viscosity, produced the most continuous films and the lowest fabric thickness. Optical microscopy and XPS analyses confirmed that when compared with SA and CMC treated fabrics, CMHPC treated fabric controlled the excessive spread and penetration of ink droplets at higher effectiveness and produced the highest color strength (K/S value) and sharpest edge. In contrast to this, SA solution exhibited the worst fluidity, the most obvious viscous behavior, and lowest zero-shear viscosity. This resulted in the most discontinuous film, highest fabric thickness, and worst printing performance. Furthermore, wettability analysis demonstrated that the film structure dependent on the rheological property was the main factor that affected the inkjet printing performance of wool fabrics. CMHPC treatment of wool fabric provides an environment-friendly method with lower CMHPC concentration, less urea consumption, and shorter steaming time for higher K/S value.

Inkjet and Extrusion Printing for Electrochemical Energy Storage: A Minireview

AbstractInkjet and extrusion printing are widely employed technologies in the field of printed electronics. They provide opportunity of manufacturing diverse electronic devices on various types of substrates by employing digital layouts under ambient conditions. In this short review, fundamentals about inkjet mechanisms and ink fluidic characteristics are presented. The interaction between individual droplets and that of droplets with substrates, which are pivotal to the printing resolution and uniformity, are analyzed. In addition, some issues on droplet‐based extrusion 3D printing are discussed as an extension of conventional inkjet printing. The recent progress in application of inkjet and extrusion printing in the field of electrochemical energy storage, ranging from batteries and supercapacitors to energy storage electrochromics, is also highlighted. Challenges and perspectives are discussed at the end. It is expected that inkjet and extrusion printing will be potent technologies to the development of electrochemical energy devices for the flexible and wearable electronics.

Water‐based poly(2‐ethylhexyl acrylate‐itaconic acid) removable adhesives with frost resistance for digital inkjet printing

AbstractAdhesives are nonmetallic materials used to bond each layer in many applications for its flexibility. For digital inkjet printing, the requirements of adhesives performance are demanding as they must be able to adhere well to adherend, be removable without leaving adhesive residue, or even causing any damage. Water‐based polyacrylates have been widely used for backing adhesive layer in application of digital inkjet printing, due to their various advantages. While the application has been limited on account of the weak frost resistance of common polyacrylates, which could not be used directly under low temperature storage. To improve the weak frost resistance, water‐based poly(2‐ethylhexyl acrylate‐itaconic acid) was synthesized. Itaconic acid (ITA) could be greatly beneficial to improve the frost resistance. The polyacrylates could still be used directly, even after being frozen below at −18°C for 16 hr. The adhesion properties of polyacrylates could also be enhanced by moderate ITA. The results show that the optimal amount of ITA was 2 mass%. The overall properties of the resulting polyacrylates with the 180° peel strength of 2.73 N/25 mm, the tack of 23 #, and the shear holding power of more than 24 hr are suitable for practical applications on removable adhesives for digital inkjet printing.