Inkjet Printing Of Inks Research Articles

Preparation and evaluation of (resorcinol – aldehyde) based polymeric dispersants for inkjet printing ink

In this study, modification of an amino polyether with resorcinol-aldehyde condensate was performed using four different aldehydes [formaldehyde, glutaraldehyde, butyraldehyde and 4-(N,N-dimethylamino)benzaldehyde] to give dispersants (1 – 5) to be used as dispersing agents for solvent based inkjet inks. The prepared dispersing agents were characterized using FT-IR and GPC. The optical properties and stability efficiency of the ink formulated with the prepared dispersing agents were investigated. The dispersants (1-5) were evaluated for their efficiency in comparison to commercial dispersing agents used in the market. Formulations of dispersants 4 and 5 showed excellent results in comparison to the commercial dispersing agents and have a good potential as effective dispersing agents for solvent based inkjet inks.

Development and Characterization of Tungsten Disulfide Ink for Ink-jet Printing

ABSTRACTIn this work, a printable tungsten disulfide (WS2) based ink is developed from readily available WS2 powder (0.6 µm average particle size), and an ink-jet printing based deposition method for a tungsten disulfide film is presented. WS2 flake coverage and bulk electrical characteristics under three different irradiance conditions are examined and discussed. Presence of excitons in the absorbance of the inks is performed by optical UV-Vis spectrometry. Metrics using the A exciton peak generated by the few-layered flakes are used to calculate the average flake lateral dimensions, the concentration of WS2 in the inks after size selection and filtering, as well as the average monolayer count of the flakes. After printing, scanning electron microscopy is used to confirm average flake lateral size and average flake area coverage, while an atomic force microscope is used to confirm flake thickness.

The Use of Carbon Nanoparticles for Inkjet-Printed Functional Labels for Smart Packaging

Smart packaging functions can be provided by printing functional labels onto packaging materials using inkjet printing and inks with changeable photoluminescence properties. Carbon nanoparticles are considered a perspective fluorescent component of such inks. Ink compositions based on carbon nanoparticles are developed and adapted for inkjet printing on paper packaging materials for producing smart packaging labels. The influence of technological factors of the printing process on the photoluminescence characteristics of the printed images is investigated. The main investigated factors are the concentration of carbon nanoparticles, the relative area of raster elements of a raster field of a tone image, the absorbance and surface smoothness of paper. The resulting parameters are photoluminescence intensity and color. It is found that in case of changes in surface smoothness and absorbance of paper and concentrations of carbon nanoparticles in the ink compositions, the photoluminescence intensity of a printed image changes while its photoluminescence color remains the same. To obtain the highest contrast of tone inkjet-printed images with carbon nanoparticles on papers with any absorbance, the highest concentration of carbon nanoparticles in the ink composition should be used. However, the highest contrast and the highest own photoluminescence intensity of a tone inkjet-printed image with inks with carbon nanoparticles can be achieved only on papers with the lowest absorbance. The most noticeable difference between photoluminescence intensity of printed images on papers with any absorbance can be obtained with the lower concentration of carbon nanoparticles in the ink composition (10 mg/mL). The optimum concentrations of carbon nanoparticles in the composition are determined: for papers with low absorbance—10 mg/mL, and for papers with medium and high absorbance—25 mg/mL. Analytical dependency is created for photoluminescence intensity of images printed with inkjet printing inks with carbon nanoparticles as a function of the studied technological factors. Some design solutions for photoluminescent labels are suggested.

Formulation and characterization of black ceramic ink for a digital ink-jet printing

Formulation of black ceramic ink and its ink-jet printability on a glass substrate were investigated. The thermal and chemical stabilities of CoFe2-xCrxO4 and Ni0.925Mn0.075Fe1.875-xCrxMn0.125O4 black inorganic pigments were analyzed with various amounts of Cr substitutions. The ceramic ink was prepared using the pigment composition that demonstrated color stability during the high temperature glazing process with a minimal Cr substitutional amount. After the dispersion stability and rheological property were optimized, the ceramic ink was suitably jetted from a print head as a single sphere-shaped droplet without satellite droplets. To improve the printability of the ceramic ink, the glass substrate was treated with a perfluorooctyl trichlorosilane (PFTS) solution. As a result, the PFTS surface treatment increased the contact angle of the ceramic ink droplets on the glass substrate and effectively minimized the ink spreading phenomena.

Photophysical properties of novel functionalized fluorescent dyes based on diketopyrrolopyrrole and application in inkjet printing ink

The novel fluorescent dyes based on diketopyrrolopyrrole materials were developed as a basic component for use in inkjet ink formulations. N-substituted DPP derivatives of ethyl formate and ethyl acetate (symmetric and asymmetric) were synthesized and characterized. Then, quantum chemical calculations were performed to investigate the observed changes in the photophysical properties of synthesized materials. Photophysical investigations of fluorescence dyes in various solvents and the effect of solvatochromism and the solubility of dyes in inkjet inks and solid state emission of dyes were used to select symmetric and asymmetric derivatives for application in inkjet formulation. In addition, the inkjet ink based on the symmetric N-substituted DPP derivatives of N,N-diethylformate and ethyl acetate was formulated. Inkjet inks were printed on polymeric substrate and their fluorescence were studied. The solubility of the asymmetric N-ethyl acetate dye in ink formulation was lower than symmetric derivatives due to stronger inter-particle interactions. From photophysical features of printed substrate, the final formulation based on symmetric ethyl acetate dye was performed for further investigation. The effect of concentration on the intensity of emission and also on the color properties (Lab) of formulation was studied. The optimum dye concentration of symmetric N,N-diethylacetate dye with highest fluorescent intensity was 0.3wt% in ink formulation. Finally, the symmetric ethyl acetate dyes formulation for security inkjet ink was performed.

Selective Laser Sintering of Conductive Inks for Inkjet Printing Based on Nanoparticle Compositions with Organic Silver Salts

Inkjet ink based on silver nanoparticles with sizes of 11.1 ± 2.4 nm has been developed. Test images are printed on a laboratory inkjet printer, followed by sintering the printed patterns with a diode laser having a wavelength of 453 nm. The structure and electrical properties of the resulting films are studied depending on the parameters of laser sintering. It is found that under optimal conditions, an electrically conductive film with a low resistivity of 12.2 μΩ· cm can be formed.

A flexible RF energy harvester using a hybrid printing technology for ‘stand-alone’ wireless sensor platforms

A flexible RF energy harvester using a novel hybrid printing technology on low-cost polymer substrates is introduced in this paper. The presented printing technology is a hybrid approach taking advantage of the low-cost flexible printing and of the high-performance surface mounting technology. The design guidelines for the hybrid printed electronics, PdCl2 catalyst ink for inkjet-printing, and material characterization method using a ring resonator are discussed in detail. A flexible RF energy harvester is designed and its performance is experimentally verified for proof-of-concept purposes. The fabricated prototype generates more than 2.9 V when it is exposed to a power density around 1 μW cm−2 at UHF radio frequency identification frequency range, demonstrating the feasibility and capability of the presented technology towards scalable conformal autonomous low-cost electronics.

Characterisation and application of pigmented UV-curable inkjet inks

PurposeThe purpose of this paper is to prepare ultra-violet (UV)-curable inkjet inks for textile printing application. The influence of both type and component ratio of monomer/oligomer on the quality of the desired viscosity range is studied. Moreover, the effect of pigment/resin ratio on the rheological behaviour of the ink has been studied.Design/methodology/approachAqueous dispersions of nanoscale organic pigments were prepared through ball milling and ultrasonication. The dispersed pigments were encapsulated into UV-curable resin via miniemulsion technique, using different types and component ratios of monomers and oligomers.FindingsIt was found that the monomer/oligomer ratio of 2:3 and the pigment/resin ratio of 2:1 gave the most stable miniemulsion dispersions and provided the most suitable rheological range for inkjet printing inks.Research limitations/implicationsAs the rheology of the ink is optimised, most of the problems associated with the jetting process could be avoided.Practical implicationsThis method of using UV-curable encapsulated inks eliminates the usage of binders, which are the principal factor for nozzle clogging of the print head. In addition, binders are responsible for the coarse handle of the printed textiles.Social implicationsThe UV-curable inks were viewed as a green technology by the US Environmental Protection Agency.Originality/valueThis method is simple and fast and requires low cost. In addition, it could find numerous applications in surface coating.

Preparation of Graphene Oxide-Based Ink for Inkjet Printing.

Fabrication of graphene-based conductive circuits via inkjet printing processes would be very significant, but preparation of graphene inks which can be used in ordinary household inkjet printer is still a challenge. Graphene oxide (GO) is an important graphene derivative with good dispersion properties in water, because it has a lot of oxygen-containing functional groups. In this paper, the relationship between the concentration of GO and the viscosity and surface tension of its dispersion were studied first, GO were prepared by modified Hummers' method. Moreover, the influence of two surfactants-sodium dodecyl sulfate (SDS) and Triton-X100 (TX-100) on viscosity and surface tension of inks were also investigated. It was found that the concentration of GO was 3.9 mg/mL, and the amount of the addition of SDS and TX-100 were 1 mg/mL and 2.5 mg/mL respectively, which can form stable GO-based inks. Finally, the resultant GO-based inks can be printed by home inkjet printer HP-1010 on normal printing paper, flexible polyimide film and thin aluminum foil. It is expected that the development of inkjet printable GO-based inks will decrease the cost of the preparation of graphene electrode/circuits and open up new ways for the application of GO-based thin film and patterns.

Recent advances in droplet wetting and evaporation.

The wetting of solid surfaces using liquid droplets has been studied since the early 1800s. Thomas Young and Pierre-Simon Laplace investigated the wetting properties, as well as the role of the contact angle and the coupling of a liquid and solid, on the contact angle formation. The geometry of a sessile droplet is relatively simple. However, it is sufficiently complex to be applied for solving and prediction of real-life situations (for example, metallic inks for inkjet printing, the spreading of pesticides on leaves, the dropping of whole blood, the spreading of blood serum, and drying for medical applications). Moreover, when taking into account both wetting and evaporation, a simple droplet becomes a very complex problem, and has been investigated by a number of researchers worldwide. The complexity is mainly due to the physics involved, the full coupling with the substrate upon which the drop is deposited, the atmosphere surrounding the droplet, and the nature of the fluid (pure fluid, bi- or multi-phase mixtures, or even fluids containing colloids and/or nano-particles). This review presents the physics involved during droplet wetting and evaporation by focusing on the evaporation dynamics, the flow motion, the vapour behaviour, the surface tension, and the wetting properties.

Thermal and laser sintering of a highly stable inkjet ink consisting of silver nanoparticles stabilized by a combination of a short chain carboxylic acid and a polymeric dispersant

A mixture of silver nanoparicles and its organic salt has been used for the development of conductive inks for inkjet printing. Silver nanoparticles stabilized with butanoic acid (C4) with the average size of 11.1±2.4 nm have been synthesized via the reduction of solid silver carboxylate with hydrazine hydrate in benzyl alcohol. An inkjet ink formulation consisting of the silver nanoparticles capped with butanoic acid (up to 50 wt.%) with the addition of polymeric BYK dispersant in a mixture of nontoxic solvents with different boiling temperatures and different polarities has been developed and its physical properties and stability have been studied. Silver layers were spin coated and printed on a polyimide film using the developed ink. Experiments on the thermal annealing of the silver films showed that the curing temperature can be below 200 °C to obtain a layer having the electrical resistivity less than 10 µΩ×cm. A study of the laser sintering of the printed and spin coated elements on a polyimide film using a diode laser operating at 453 nm in impulse mode showed that the best mode is a multi-pass sintering, which can be divided into two steps: the evaporation of the solvent and sintering of the silver nanoparticles.

Continuous hydrothermal flow synthesis of Gd‐doped CeO2 (GDC) nanoparticles for inkjet printing of SOFC electrolytes

AbstractGdxCe1‐xO2‐δ (GDC) nanoparticles were synthesized, using continuous hydrothermal flow synthesis. By varying the synthesis conditions, particle size and morphology could be tailored. Here, particle sizes between 6 and 40 nm with polyhedral or octahedral shape could be obtained. Gd0.2Ce0.8O2‐δ nanoparticles were further processed into inks for inkjet printing. Despite the small particle size/large surface area, inks with excellent printing behavior were formulated. For proof‐of‐concept, thin GDC layers were printed on a) green NiO‐GDC substrates, and on b) presintered NiO‐YSZ substrates. While no dense layers could be obtained on the green NiO‐GDC substrates, GDC nanoparticles printed on NiO‐YSZ substrates formed a dense continuous layer after firing at 1300°C.

Zirconia UV-curable colloids for additive manufacturing via hybrid inkjet printing-stereolithography

Currently, additive manufacturing of ceramics by stereolithography (SLA) is limited to single materials and by a poor thickness resolution that strongly depends on the ceramic particles-UV light interaction. Combining selective laser curing with inkjet printing represents a novel strategy to overcome these constrains. Nonetheless, this approach requires UV-curable inks that allow hardening of the printed material and sintering to high density. In this work, we report how to design an ink for inkjet printing of yttria stabilized zirconia (YSZ) which can be impressed by addition of UV-curable monomers. We especially show how the formulation of the inks and particularly the UV-monomer concentration impacts the printability and the UV-curing. This leads to prints that are resistant to solvent washing first and densify to 96% dense YSZ layers after sintering.

Formulation and Evaluation of Glass-Ceramic Ink for Digital Ink-jet Printing

Formulation and Evaluation of Glass-Ceramic Ink for Digital Ink-jet Printing

Inkjet-printing line film with varied droplet-spacing

Abstract Compared to the conventional cell-shaped pixel structure, linear bank structure for solution-processed organic light-emitting diode (OLED) displays has the advantage of simple process, and large aperture-ratio. However, the prolonged drying time of the inkjet-printed ink in the linear bank forms a convex surface profile in the longitude direction. To achieve uniform film surface of the inkjet-printed poly (3,4-ethylenedioxythiophene):poly (styrenesulfonate) (PEDOT:PSS), a novel printing method by varying the droplet-spacing is introduced. It is found that a larger droplet density at the line ends than that at the line center can compensate the inward flow of the ink, enabling systematic control of the film thickness along the line direction. As a result, uniform PEDOT:PSS line pattern is achieved. OLED display panels with line pixels are fabricated with varied droplet-spacing demonstrating better brightness uniformity than those inkjet-printed with constant droplet-spacing.

In situ preparation of silver nanoparticles decorated graphene conductive ink for inkjet printing

Conductive ink can be widely applied in printed electronics to print high conductivity and flexible electrodes, especially for large-area formats with low cost considerations. In this article, we demonstrated that the in situ prepared silver nanoparticles decorated graphene conductive ink was suitable for flexible electronics. By using liquid phase exfolication method and reducing the silver salt to nano silver at the same system which addressed the heterogeneous issue of silver decorated graphene. The inkjet-printed graphene features attained low resistivity of 20 ± 1Ω/□ after a thermal anneal at 400 °C for 30 min while showed uniform morphology, compatibility with flexible substrates.

Preparation of Poly(styrene)-b-poly(acrylic acid)-Coupled Carbon Dots and Their Applications.

Carbon dots (CDs) are covalently coupled to the poly(acrylic acid) (PAA) block of polystyrene-b-poly(acrylic acid) (PS-b-PAA). The produced amphiphilic PS-b-PAA-CD shows excellent solubility and micellar formation in selective solvents. Transmission electron microscopy study shows that the micelle of PS-b-PAA-CD in water (a PAA-selective solvent) has a strawberry-like shape with the CDs as patches on the PAA corona surface although that in toluene (a PS-selective solvent) has a reversed shape with the CDs in the core. The fluorescence intensity of PS-b-PAA-CD in water is approximately twice that in toluene because the close contacts between the CDs in the core of the micelle lead to decreased fluorescence intensity due to π-π interactions. Thus, PS-b-PAA-CD can be used in sensors via fluorescence quenching through morphology control of micelle by solvent selectivity. The PS-b-PAA-CD aqueous solution is successfully used as an fluorescent ink for inkjet printing and fluorescent fillers for poly(methyl methacrylate) (PMMA) composites. The quantum yields of the CDs in pure CD, PS-b-PAA-CD, and a PMMA/PS-b-PAA-CD composite were almost the same (∼41%). Because of its good solubility in organic solvents and self-assembly property in solution, the application scope of PS-b-PAA-CD can be further expanded in the future.

Comparison of thermal decomposition and chemical reduction of particle-free silver ink for inkjet printing

Two current major methods (thermal decomposition of silver organic salts and chemical reduction of silver salts) to formulate a particle-free silver ink are compared. X-ray diffraction (XRD) and scanning electronics microscopy (SEM) are used to investigate the printed silver patterns from conductive inks made from those two methods. Both processes are shown to make silver with high purity from XRD results. SEM images indicate that chemical reduction can make denser silver film than thermal decomposition. Thermogravimetric analysis and Differential thermal analysis indicates that the silver film is formed at very low temperature compared with thermal decomposition. This phenomenon may be caused by volume shrinkage of silver precursor decomposition after thermal sintering. The resistivity of printed silver patterns made by chemical reduction is also lower than the silver patterns made by thermal decomposition because of less porosity. Also, our results show that a polymer additive can render the silver film more uniform and easier to be sintered.

Ink for Ink-Jet Printing of Electrically Conductive Structures on Flexible Substrates with Low Thermal Resistance

The development of new technologies in electronics related to flexible polymeric substrates forces the industry to introduce suitable tools (special type of dispensers) and modern conductive materials for printing electronic circuits. Moreover, due to the wide use of inexpensive polymeric foils (polyethene, PE, or poly(ethylene terephthalate), PET), there is a need to develop materials with the lowest possible processing temperatures. The present paper presents the selection criteria of suitable components and their preparation for obtaining electrically conductive ink with a special nanosilver base. In the case of the discussed solution, all components allow to make circuits in relatively low sintering temperature (even below 130°C). Additionally, the authors show the most significant ink parameters that should be taken into consideration during Research and Development (R&D) works with electrically conductive inks. Moreover, ink stability parameters are discussed and some examples of printed circuits are presented.

Silver-based reactive ink for inkjet-printing of conductive lines on textiles

Silver is the material of choice for printed electronics. However, dispersed silver particles can block the fine nozzles of an inkjet print head and after printing the patterns have to be sintered at elevated temperatures to provide high conductivity. In this work we investigated and optimized the printing of a reactive silver ink which contains silver in complexed form, therefore avoiding disadvantages of particle dispersions. After printing the complexed silver is transferred into metallic by evaporating the complexing ligands at 50°C. The ink contains around 11% silver and has a surface tension of 26mNm−1. It is stable for at least 1month at room temperature and for at least 3months at 2–8°C. The ink was tested on several substrates and an application on textile is shown. The inkjet printed electronic circuit paths on the fabric withstand washing tests, moisture, and heat as well as crumpling.