Inkjet Ink Research Articles

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.

Inkjet printing bendable circuits based on an oil-water interface reaction

Bendable circuits were precisely fabricated by inkjet printing technology based on an oil-water interface reaction. Silver amine ion aqueous solution was used as inkjet ink, and liquid polydimethylsiloxane (PDMS) added reducing agent was served as printing substrate. Oil-water interface patterns were fabricated with inkjet printing technology. Then an oil-water interface reaction was carried out to generate silver circuit. It is demonstrated that the water phase could wet well the oil phase for generating a thick and compact silver layer by adding a small amount of surfactant. A mosaic silver layer with 15–20 μm thickness was obtained on the PDMS surface. The bendability of the inkjet printed circuit was greatly improved with the mosaic structure. This work presents a facile way to fabricate bendable circuits by inkjet printing technology.

Thermal bubble inkjet printing of water-based graphene oxide and graphene inks on heated substrate

Stable-jetting water-based graphene oxide (GO) and graphene (GR) inks without any surfactant or stabilizer are prepared from an unstable-jetting water-based starting solvent, with many thermal bubble inkjet satellite drops, by simply increasing the material concentration. The concentration-dependent thermal bubble inkjet droplet generation process is studied in detail. To overcome the low concentration properties of water-based thermal bubble inkjet inks, the substrate temperature is tuned below 60 °C to achieve high-quality print lines. Due to the difference in hydrophilicity and hydrophobicity of the 2D materials, the printed GO lines show a different forming mechanism from that of the GR lines. The printed GO lines are reduced by thermal annealing and by ascorbic acid, respectively. The reduced GO lines exhibit electrical conductivity of the same order of magnitude as that of the GR lines.

New Yellow Synergist for Stable Pigment Dispersion of Inkjet Ink

Minimizing ink droplet and self-dispersed pigment mixture are becoming hot issues for high resolution of inkjet printing. New synergist including sulfonic acid group of PY-74 was suggested and synthesized. Pigment itself did not show water solubility but new synergist, SY-11 exhibited good solubility in water and organic solvents such as DMSO and DMF. When aqueous pigment ink was prepared with SY-11, storage stability of the ink has been remained for 7 days under periodically repeated heating and cooling conditions. Particle size of formulated ink was around 150 nm.

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.

Reactive Silver Oxalate Ink Composition with Enhanced Curing Conditions for Flexible Substrates.

A solid silver-ligand complex, μ-oxolato-bis(ethylenediaminesilver(I)), was developed for formulating particle-free conductive metal-organic decomposition (MOD) inkjet inks. The complex comprises both a high molar silver content and solubility in inkjet compatible polar solvents. An aqueous ink formulation with 29.5 wt % silver content was developed and inkjet printed onto glass, polyethylene terephthalate, and polyimide substrates. A new hybrid thermal-photonic curing approach resulting in substantially improved electrical properties and substrate adhesion is presented. Silver conductive traces were measured to have bulk resistivity of 4.26 × 10-8 Ω m, which is 2.7 times that of bulk silver. One-pot complex synthesis yielded an easily isolated, and stable, solid product that can be formulated when needed thereby improving shelf life.

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.

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.

On International Standards for In-flight Measurements of Inkjet Drops

The first International Electrotechnical Commission (IEC) standards for vision-based measurements of inkjet droplet speed and volume from inkjet print-heads were recently prepared for publication by the Technical Committee working group WG3 for Printed Electronics equipment. These IEC/ISO standards could be more widely adopted for other inkjet printing applications and establishing the relative performance of drop-on-demand (DoD) inkjet print-heads and inks. The underlying behavior of inkjet drops and effects influencing these standards for in-flight drop measurement methods are discussed.

Printability of papers recycled from toner and inkjet-printed papers after deinking and recycling processes.

In our contemporary world, while part of the fibers used in the paper industry is obtained from primary fibers such as wood and agricultural plants, the rest is obtained from secondary fibers from waste papers. To manufacture paper with high optical quality from fibers of recycled waste papers, these papers require deinking and bleaching of fibers at desired levels. High efficiency in removal of ink from paper mass during recycling, and hence deinkability, are especially crucial for the optical and printability quality of the ultimate manufactured paper. In the present study, deinkability and printability performance of digitally printed paper with toner or inkjet ink were compared for the postrecycling product. To that end, opaque 80 g/m2 office paper was digitally printed under standard printing conditions with laser toner or inkjet ink; then these sheets of paper were deinked by a deinking process based on the INGEDE method 11 p. After the deinking operation, the optical properties of the obtained recycled handsheets were compared with unprinted (reference) paper. Then the recycled paper was printed on once again under the same conditions as before with inkjet and laser printers, to monitor and measure printing color change before and after recycling, and differences in color universe. Recycling and printing performances of water-based inkjet and toner-based laser printed paper were obtained. The outcomes for laser-printed recycled paper were better than those for inkjet-printed recycled paper. Compared for luminosity Y, brightness, CIE a* and CIE b* values, paper recycled from laser-printed paper exhibited higher value than paper recycled from inkjet-printed paper.

Improved Water-Resistance Test Methods Utilizing a Multispectral Imaging System to Quantify Black and Color Ink Bleeding for Plain Paper Office and Legal Documents Printed with Pigment- and Dye-Based Inkjet Inks

Current ISO standards that pertain to water-resistance testing with inkjet prints were developed for moisture-impermeable RC photo papers and do not take into account the kinds of ink diffusion behavior that can occur with inkjet printing on highly absorbent plain papers, especially with dye-based inks. Contact with water with plain paper documents can result in significant lateral ink bleeding, migration of inks through the paper to the backside of the sheet, transfer of ink from one sheet to adjacent sheets, and two-way transfer of inks with double-sided printed documents. Shipping labels and envelopes can become illegible should they become wet, and Barcodes and QR codes may be rendered completely unreadable. This study attempts to better understand the water-resistance behavior of plain paper documents printed with dye-based and pigment inkjet inks. The use of high-resolution multispectral imaging and colorimetric analysis systems to provide a quantitative assessment of ink bleeding, migration, and ink transfer to adjacent pages is explored as an alternative to the subjective, qualitative, water-resistance evaluation methods specified in current ISO standards.

Tuning inkjet printability of hydroxypropylated-starch-based coatings by mineral selection

Coatings based on hydroxypropylated starch (HPS) provide extraordinary print density with dye-based inkjet inks, but their suitability for pigment-based inks can be limited due to inadequate carrier medium (water) absorption and colorant fixation. In the present work, HPS-based coatings were tailored for both a pigmentbased and a dye-based ink by adding silicate minerals or acid clay (both Lewis and Brönstedt acid sites present in the acid clay). Substrate-ink interaction and colorant distribution were investigated via uncoated gloss and print quality indicators such as print density, ink bleeding tendency and delta gloss after printing with desktop printers. Three-dimensional z-stack CLSM images taken from printed samples revealed substantial differences in ink holdout and penetration characteristics between the studied materials. Pigment-filled HPS coatings showed up to 60% increase in print density compared to uncoated reference substrate and an increase of up to 35% compared to plain HPS coating with dyebased inks. In case of pigment-based ink, the increase was 17% between plain HPS coating and acid-clay-filled HPS coating. In addition, a combination of HPS and silicate mineral decreased ink bleeding substantially, but lower print gloss compared to substrate initial gloss was observed with the majority of experimental coatings. It was found that the pigment type affects substantially the unprinted gloss, which is naturally high in the case of pure HPS coating, but also the observed drastic difference in substrate permeability may explain the differences in print quality. The findings suggest that coating morphology, together with chemical interactions between starch and mineral and coated substrate and ink, has a key role in achieving high gloss and good print quality.

Synthesis, characterization and ultrafiltration of reactive dyes. Application by exhaustion and/or ink-jet printing. IV.

Three new bis azo reactive dyes of different metallic salts (Na, K, Li) were synthesized. The synthesis was obtained by diazotization of 4-amino-2:5 di methoxy phenylene-beta hydroxyl ethyl sulphone sulphate ester and coupling with 1-amino-8-hydroxynaphthalene-3,6-disulfonic acid (H-acid) (moles ratio 2:1). The dyes were purified-concentrated by ultrafiltration technology, characterized and applied on cotton, wool and nylon 6,6 fabric by exhaustion (dyeing) and by ink-jet printing. Fastness properties of the dyeings were measured. Wash fastness was investigated according to international standard methods and was found to be very good to excellent in all cases, while light fastness values were medium to low. Ink-jet ink formulations were prepared using the ultra filtrated reactive blue dyes UF RB(a-c) and their properties pH, conductivity, surface tension and viscosity were monitored over a period of 90 days. The inks were used to print digitally cotton and nylon 6,6 samples and wash- and light fastness properties of the prints were measured. Wash fastness properties were excellent while light fastness values are low Colour measurements of the dyeings and prints were conducted.

The Capability of Raman Microspectroscopy to Differentiate Printing Inks.

This study applies Raman microspectroscopy to differentiate the chemical components in printing inks of different brands, colors, and type using the 532 nm and 785 nm excitation wavelengths. Spectra were collected from 319 inks (78 inkjet, 76 toner, 79 offset, and 86 intaglio) representing various colors. Comparisons were performed to calculate discrimination capability percentages for each ink type. Overall, Raman microspectroscopy differentiates according to the following hierarchy: intaglio (96%), inkjet (92%), offset (90%), and toner (61%). The ability of Raman microspectroscopy to differentiate between same-colored inks from different brands was dependent on the color and ink analyzed. Based on ink color, the discrimination capability ranged from 75 to 94% (inkjet), 0 to 86% (toner), and 0 to 77% (offset). Copper phthalocyanine was detected in cyan inks and various intaglio inks, while carbon black was identified in black inkjet, offset, and intaglio inks.

VOCs monitoring of new materials for ceramic tiles decoration: GC–MS analysis of emissions from common vehicles and inkjet inks during firing in laboratory

The decoration of ceramic tiles “ink-jet revolution” has brought significant advantages to tiles manufacturing, but the explosive diffusion, until 4–5 years ago, of this technique has not been accomplished by an adequate scientific research. Among all the features that have to be studied yet, one of the most important is the influence of the new generation inks on the total emission at ceramic chimneys. In this paper, we present a first characterization of emissions from a set of commercial inks and vehicles: they were collected by propter firing of samples in an electric kiln and analyzed by GC–MS. This study is part of a larger research project, which includes the chemical characterization and the evaluation of thermal behavior of inks and vehicles by TG-DTA and other techniques. The obtained results permit to divide common vehicles into 3 classes, depending on their thermal behavior and emissions pattern. Inks, most of which present an ester based formulation, sometimes mixed with glycols or paraffins, follow the behavior of their single components. The most common formulation leads to the presence in the emission pattern of evaporation products (2-ethylhexyl esters of lauric, myristic, decanoic and octanoic acids) and decomposition products (mainly aldehydes and 2-ethyl-1-hexanol).

Flexible hybrid circuit fully inkjet-printed: Surface mount devices assembled by silver nanoparticles-based inkjet ink

Nowadays, inkjet-printed devices such as transistors are still unstable in air and have poor performances. Moreover, the present electronics applications require a high degree of reliability and quality of their properties. In order to accomplish these application requirements, hybrid electronics is fulfilled by combining the advantages of the printing technologies with the surface-mount technology. In this work, silver nanoparticle-based inkjet ink (AgNP ink) is used as a novel approach to connect surface-mount devices (SMDs) onto inkjet-printed pads, conducted by inkjet printing technology. Excellent quality AgNP ink-junctions are ensured with high resolution picoliter drop jetting at low temperature (∼150 °C). Electrical, mechanical, and morphological characterizations are carried out to assess the performance of the AgNP ink junction. Moreover, AgNP ink is compared with common benchmark materials (i.e., silver epoxy and solder). Electrical contact resistance characterization shows a similar performance between the AgNP ink and the usual ones. Mechanical characterization shows comparable shear strength for AgNP ink and silver epoxy, and both present higher adhesion than solder. Morphological inspections by field-emission scanning electron microscopy confirm a high quality interface of the silver nanoparticle interconnection. Finally, a flexible hybrid circuit on paper controlled by an Arduino board is manufactured, demonstrating the viability and scalability of the AgNP ink assembling technique.

Study of Vis-NIR and NIR spectral data of black inkjet prints using principal component analysis for forensic discrimination

The aim of this work was to prepare spectral data for principal component analysis and to examine 19 samples of six different brands. Samples consisted of the same type of office paper with black areas printed in black ink only. The spectral data were acquired by fibre optics reflection spectroscopy in Vis-NIR and only NIR (Vis-NIR FORS) directly on paper. The black inkjet-printed samples were analysed with regard to the forensic analysis of documents. The method used is based on the combination of molecular spectroscopy in the visible (Vis) and near infrared region (NIR) combined with a chemometric method, – principal component analysis (PCA). The PCA method divides the inkjet inks sample into clusters. It was found out that by a combination of spectrum pre-processing methods and principal component analysis, it is possible to separate inks containing carbon black from the other inks using other organic colourants. This method appears to be a useful tool for forensic examination of printed documents containing inkjet inks. Spectra of inkjet inks were acquired without any destructive or invasive procedure, for example cutting sample or for extraction with the possibility to measure out of the laboratory.

Metal Nanoparticles Based Inkjet Ink for Advanced Circuit Board Application

This study investigates the synthesis of mono metallic (copper and silver) and bi-metallic (copper/silver core/shell) conductive nanopigments for inkjet printing. Polyethylene glycol (PEG) was used as a main reducing agent followed by polyvinylpyrrolidone (PVP) as a capping and dispersing agent. From the XRD, TEM, and SEM analyses, the synthesized mono and bi metallic particles were con?rmed to be in a nano scale with particle size 7, 8.5 and 15.5 nm for copper, silver and copper/silver core/shell, respectively. The prepared nanopigments were included in inkjet ink formulation and printed on flexible polyethylene terephthalate (PET) films. The printed ink films were sintered at various temperatures (110, 150, 200). The results revealed that the resistivity of these particles was reduced by sintering and the resistivity of Cu, Ag and Cu/Ag patterns sintered in air at 200 ºC for 30 min were 3.1, 2.99 and 4.14 µ?-cm, respectively. The obtained results were in a good agreement with the published ones and insured the promising using of our products in metal-based inkjet printed circuit boards (PCB).

Lubrizol buys Diamond Dispersions to boost its offerings to the inkjet inks market

We demonstrate that a flexible dielectric-barrier-discharge (DBD) plasma actuator fabricated by an inkjet printing process using metallic inks generates stable surface discharge and ionic wind for active airflow control. The establishment of a practical fabrication method for DBD plasma actuators is a critical issue to be tackled for industrial applications. The inkjet process requires just the printing of the metallic inks and sintering processes while the conventional photolithography technology requires a lot of processes for the fabrication of the DBD plasma actuators. The electrical and mechanical characteristics of a multi-stage DBD plasma actuator fabricated by this printed electronics technology are investigated and are compared with the DBD plasma actuator made by the conventional method using copper tape. The DBD plasma actuator developed in this study induces a similar or even stronger ionic wind than that of the conventional one. Also, a thin exposed electrode (≃1 μm), which is preferable in terms of airflow control applications, is achieved by the inkjet printing process. The development of the fabrication method using printed electronics expands the application field of the DBD plasma actuator, including complex curved surfaces and full-scale size applications.

Wetting of Inkjet Polymer Droplets on Porous Alumina Substrates.

The resolution of inkjet printing technology is determined by wetting and evaporation processes after the jet drop contacts the substrate. Here, the wetting of different picoliter solubilized polymer droplets jetting onto one-end-closed porous alumina was investigated. The selected polymers are commonly used in inkjet ink. The synergistic effects of the hierarchical structure and substrate surface modification were used to control the behavior of polymer-based ink drops. A model that invokes the effect of surface tension was applied to calculate the amount of polymer solution penetrating into the pores. The calculation corroborates experimental observations and shows that the volume of polymer solution in the pores increases with an increase in pore radius and depth, resulting in less solution remaining on the substrate surface. The structure of the porous substrate coupled with intrinsic polymer properties and surface modifications all contribute to the resolution that can be achieved via inkjet printing.