Inkjet Print Quality Research Articles

Enhancement of hydrophilicity and color strength in plasma treated PET with water vapor post-exposure using a new in-line pilot scale DBD plasma

Due to its low hydrophilicity, direct sublimation inkjet printing on woven polyester fabric surfaces is challenging. This research experimentally studies the efficacy of dielectric barrier discharge (DBD) roll-to-roll plasma treatment with or without water vapor post-exposure as a novel method to modify polyethylene terephthalate (PET) surfaces to enhance hydrophilicity, color performance, and printing quality. The Response Surface Methodology (RSM) was used to design experiments, and the optimum conditions were analyzed through statistical calculations. Their results were examined using Optical Emission Spectroscopy (OES), Atomic Force Microscopy (AFM), field emission scanning electron microscopy (FESEM), Energy Dispersive X-ray (EDX), X-ray Photoelectron Spectroscopy (XPS), and Attenuated Total Reflectance Fourier Transform Infra-Red spectroscopy (ATR-FTIR) tests. Qualitative and quantitative tests for color performance and wicking test used for hydrophilicity assessment confirms the effectiveness of this Green inline pretreatment for industries to enhance direct sublimation inkjet printing quality on PET by a decrease in absorption time from 12051 to 202 s and an increase in the color depth to 12.49%, 25.89 and 18.07% for Cyan, Magenta and Key (black) respectively. One of the stable optimum conditions in which three printed colors: Cyan, Magenta, and Black (Key), show high-quality color performance is at 15 processing rounds, 2 m/min velocity in the absence or presence of water vapor post-exposure. Water vapor post-exposure exhibits a beneficial, economic effect along with plasma treatment. The results show that the chemical modification aspect of this treatment plays a more significant role in printing quality enhancement than its morphological modification.

Effects of MDF Substrate Surface Coating Process on UV Inkjet Print Quality

The structural properties and whiteness of the substrate surface markedly effect printing quality and are closely related to the primer coating processes. Herein, four different roller coating schemes were applied on MDF surfaces to change their structural properties and color, and the whiteness, gloss, and roughness properties of the substrate surfaces were characterized for UV inkjet printing. Data analysis was conducted to explore the effects of these variables on the color reproduction, relative contrast, and printing gloss of the MDF substrates. The results showed that, according to CMYK, L*a*b* values and spectral reflectance data, the finishing of the MDF substrate with a 40 g/m2 layer of transparent primer combined with three layers of white primer at 20 g/m2 per roll coating layer had the best color reproduction effect for UV inkjet printing. Regarding the effects of relative contrast, the correlation with whiteness and glossiness was significant, while the correlation with glossiness was minor. The inkjet printing gloss value was positively correlated with substrate primer surface whiteness, while it was negatively correlated with roughness. When the surface whiteness of the substrate was relatively high, the roughness was lower and the printing effects were glossier. We sought to optimize the printing effects of all aspects of the MDF substrate by primer coating. The results of this work provide a feasible application method to improve printing quality and enhance the added value of low-quality boards, as well as to further expand the application of UV inkjet printing in the wood decoration market.

Optical‐physical and inkjet printing properties of created hybrid CaCO3 coated papers

AbstractThe aim of this study is to examine the role of different formulations of calcium carbonates on the inkjet printing quality, with the use of cationic carboxymethyl cellulose (CMC)‐starch as a binder in the formation of the coating structure of paper to use for inkjet printing. For this, GCC (ground calcium carbonate), PCC (precipitated calcium carbonate) and ECC (eggshell calcium carbonate), which have been tried as new coating materials in recent years, are mixed in different proportions to form a different coated formulation and plastered on the newly produced paper surface. Then, optical and physical tests of the obtained samples are carried out. Then, printing properties of the papers on which drop‐on‐demand system inkjet printing is made are examined. According to the obtained data, it is determined that the optical properties of coated paper with GCC + PCC blends outperformed papers coated with other blends. According to the physical test results, GCC + PCC blended coated papers showed the best performance in breaking length and tear indices. ECC + PCC blended coated papers however showed the best performance in burst indices. It is determined that as the particle size of the calcium carbonates in the coating materials decreased, the burst indices value also decreased. This situation is the opposite for breaking length and tear indices values. When the inkjet printing features are examined, it is seen that the best results are obtained from GCC + ECC coated papers in general. The most optimal metamerism indices results, measured under three different light sources, are obtained on GCC + PCC coated papers.

The distribution of poly-DADMAC additive in the inkjet coating layer and its influence on the print quality

Maximizing the functionality of cationic polydiallyldimethylammonium chloride (poly-DADMAC) additive with minimal dosage in inkjet coatings can contribute to both an improvement in quality and a cost reduction. To do this, it is essential to understand how the cationic additive is distributed in the coating layer and how it affects the print quality. This study presents a three-step investigation to enhance the understanding of the distribution of poly-DADMAC, as well as its effect on inkjet print quality. First, the adsorption behavior of poly-DADMAC on silica pigments was investigated by measuring the surface charge of silica and the adsorption of the cationic additive. Second, the influence of poly-DADMAC on the printability of binder films was investigated. Finally, the effect of poly-DADMAC on the print quality of inkjet paper was examined. The addition of poly-DADMAC improved the print quality of the inkjet paper because of the improved holdout of the negatively charged colorants in the ink.

Influence of the surface characteristics of corrugated cardboard on the quality of inkjet printing

This paper investigates the quality of inkjet printing on corrugated cardboard with various characteristics such as the presence of surface coating, the type of cardboard structure, the corrugated layer profile, and the corrugated cardboard height. The color characteristics of the corrugated board surface of studied samples were analyzed in the CIE Lab system; the value of the discrepancy in the shade of white was established when compared with the reference values of the ISO 12647 standard. During the study, the main criteria for assessing the quality of color reproduction of inkjet imprints were analyzed: an indicator of the general contrast level (K), the value of color differences for the basic tone shades (ΔE), and the volume of the body color coverage (ΔE2). It was found that when printing on various types of corrugated cardboard, there is a general decrease in the overall contrast value. The actual level of color differences is ΔE=10...45 and exceeds the permissible standards for the color reproduction quality. This adversely affects the reproduction of different color tones in the printed image. In general, the quality of color reproduction differs for the test samples of corrugated cardboard in terms of the magnitude of the spread in the values of color distortions on the tone shades. The influence of the main characteristics of the investigated samples of corrugated cardboard on the quality indicators of inkjet printing has been analyzed. In particular, a significant influence of the index of color characteristics of the surface of corrugated cardboard L* and the type of corrugated board structure on the quality of color reproduction has been established. The study results reported here could make it possible to reasonably approach the selection of the corrugated board structure that is optimal in composition, increase the productivity of the technological process for manufacturing containers, and stabilize the quality of printing on corrugated cardboard

Controlling the Spreading of Nanoliter-Scale Droplets on the Fibers of Fabrics for Enhancing Image Quality and Ink Utilization.

Electronic and traditional textiles have been widely manufactured through inkjet printing. However, nanoliter-scale ink droplets tend to excessively spread along the fiber direction, which results in poor image quality and low ink utilization. Here, hydroxyethyl cellulose (HEC) and hydroxypropyl methyl cellulose (HPMC) were introduced to control the spreading of nanoliter-scale droplets on cotton fabrics. The results showed that both HEC and HPMC could reduce the spreading of nanoliter droplets along the fibers through increasing the hydrophobicity of the fabric. However, the effect of HPMC was much better than that of HEC due to its higher surface activity. The flow of nanoliter droplets along the fibers was well consistent with the Washburn function. After HPMC treatment, the depositing length of one droplet reduced from beyond 200 μm to about 50 μm. The imaging quality was greatly improved. In addition, the dye utilization increased by 33-78% due to the decrease in the diffusion of dye solution to the back of the fabric. This study is of great significance for improving the quality of inkjet printing and the utilization of depositing materials, particularly expensive materials.

Enhancing drop mixing in powder bed by alternative particle arrangements with contradictory hydrophilicity

BackgroundDrop mixing in porous media is critical to printing quality of inkjet printing and binder jetting 3D printing, however, the mixing is poor due to restricted pore space. In this study, an alternative hydrophobic/hydrophilic particle arrangement was proposed to enhance dual droplets mixing in a powder bed. MethodsA computational fluid dynamic (CFD) model was first developed to simulate the fluid flow for drops falling on a powder bed by using volume of fluid (VOF) technique. Two drops containing separate solutes sequentially impact an assembly of particles. An index of mixing was proposed to quantitatively describe the degree of mixing by calculating the standard deviation of species concentrations. Significant FindingsTo enhance mixing, a new approach was developed to improve liquid mixing by arranging hydrophobic/hydrophilic particles alternatively. Furthermore, drops falling with a horizontal offset was shown to prolong the vorticity for convective mass transportation. With an optimal offset distance of 15μm, the mixing degree can be enhanced from 34.2% to 56.2%. The printing strategy developed from this study could apparently enhance drop mixing in porous media and provided potential developments for multiple-component mixing in binder jetting 3D printing.

The retraction of jetted slender viscoelastic liquid filaments

Long and slender liquid filaments are produced during inkjet printing, which can subsequently either retract to form a single droplet, or break up to form a primary droplet and one or more satellite droplets. These satellite droplets are undesirable since they degrade the quality and reproducibility of the print, and lead to contamination within the enclosure of the print device. Existing strategies for the suppression of satellite droplet formation include, among others, adding viscoelasticity to the ink. In the present work, we aim to improve the understanding of the role of viscoelasticity in suppressing satellite droplets in inkjet printing. We demonstrate that very dilute viscoelastic aqueous solutions ($\text {concentrations} \sim 0.003\,\%$ wt. polyethylene oxide, corresponding to nozzle Deborah number$De_{n}\sim 3$) can suppress satellite droplet formation. Furthermore, we show that, for a given driving condition, upper and lower bounds of polymer concentration exist, within which satellite droplets are suppressed. Satellite droplets are formed at concentrations below the lower bound, while jetting ceases for concentrations above the upper bound (for fixed driving conditions). Moreover, we observe that, with concentrations in between the two bounds, the filaments retract at velocities larger than the corresponding Taylor–Culick velocity for the Newtonian case. We show that this enhanced retraction velocity can be attributed to the elastic tension due to polymer stretching, which builds up during the initial jetting phase. These results shed some light on the complex interplay between inertia, capillarity and viscoelasticity for retracting liquid filaments, which is important for the stability and quality of inkjet printing of polymer solutions.

Synergetic effect of cationic starch (ether/ester) and Pluronics for improving inkjet printing quality of office papers

Improving the printability of paper is still a relevant challenge, despite the fast development of digital communications. While it is well-known that cationic starches enhance ink density, their commercial paper-grade forms are limited to ethers with low degree of substitution. This work addresses the underexplored potential of highly substituted cationic starch for paper coating and its combination with tri-block polymers, namely Pluronics (P123 and F127), taking advantage of their supramolecular interactions with amylose chains. For that purpose, cationic starch ether and ester (starch betainate), both with a degree of substitution of 0.3, were synthesized by alkaline etherification and by transesterification, respectively. Paper without any surface treatment was subjected to one-side bar coating with suspensions encompassing those products and Pluronics, besides other common components. Black, cyan, yellow and magenta inks were printed on all coated papers through an inkjet printer. Key properties of printing quality such as the gamut area, gamut volume, optical density, print-through, inter-color bleed and circularity were measured in a controlled temperature-humidity environment. For instance, a formulation with cationic starch (ether/ester) and P123 improved the gamut area by 16–18% in comparison to native starch-coated paper sheets. Interestingly, the individual assessment of each component showed that cationic starch ether, starch betainate and P123 only improved the gamut area by 5.6%, 8.9% and 6.8%, respectively. Finally, but not less importantly, starch betainate was found to quench optical brightening agents to a lesser extent than cationic starch ethers.

The research progress in recording layer of the inkjet printing materials

AbstractInkjet printing has become a prevailing printing technology due to its practicability and rapidity. The color inkjet printing as one of the inkjet printing has color comprehensive and high clarity compared with traditional printing. The key point of the color inkjet printing is the introducing of special recording layer which has great influence on the printing quality. However, the printing quality of the color inkjet printing depends on the compositions and performance of the recording layer and the infiltration behavior between the ink and the recording layer. Specially, the theoretical study of the infiltration behavior between the ink and the recording layer is the key to guiding the structural design. In this review, the types and compositions of the recording layer were clearly analyzed, the process and evaluation methods of ink infiltration and the performance evaluation system of the recording layer were also summarized. Ultimately, the current bottleneck and the development trend of the recording layer were put forward.

Influence of primers on the optical characteristics of ink-jet imprints

The quality of ink-jet printing depends to a large extent on the technical characteristics of the selected equipment and the surface properties of the printed substrates. It is known that for digital printing it is necessary to use expensive paper with a special coating that determines the degree of gloss of the surface. Therefore, ordinary offset papers before ink-jet printing are covered with primers that ensure good fixation of pigment ink or dye on paper, a wide field of color coverage, characteristic gloss, which generally contribute to high quality of imprints. As you can see, the type of the substrate and the state of its surface has a very great influence on the quality of the imprints. Result of the research, it has been confirmed that not only expensive paper of a special purpose can be used for a drop ink-jet digital printing. High-quality color imprints can also be obtained on ordinary offset and coated paper, coated before printing with special primers based on interpolymeric complexes of polyvinyl alcohol, which will provide sufficient optical density, contrast of images, and expand the possibilities of digital ink-jet printing.

Effect of the primer on barcode quality in ink-jet printing

It has been proposed to modify the surface of offset and coated paper with a special coating (primer) that ensures the high quality of ink-jet printing, specifically barcodes. The application of digital ink-jet printing using aqueous-based inks makes it difficult to achieve the required print quality on conventional paper. Ink-jet printing is widely used in the production of customized packaging and labeling products. Given that this type of products contains the printed barcode, it is necessary to ensure its functionality (readability) after printing.The primer ensures a controlled process of ink absorption at ink-jet printing, thereby improving the print quality. To this end, a composition of the primer was used on the basis of a water solution of the interpolymeric complex of polyvinyl alcohol (PVOH) and polyvinylpyrrolidone (PVP).The influence of the primer that contains different amounts of the interpolymeric complex on a change in the water contact angle of imprinted paper has been investigated.Prints on paper with and without the primer were obtained using an ink-jet printing method; quality of the line and barcode print was assessed. Such quality indicators for the line were defined as a line width on the imprint, a line blurriness at the line-paper interface, a line raggedness, and the optical density. In addition, the primer's effect on the barcode print quality at ink-jet printing was investigated.The study results make it possible to ensure the high quality of barcode printing on conventional print papers by using an ink-jet printing method. Applying the primer improves the line and barcode print quality. The barcode quality grade increases from the lowest (unacceptable) score of 0 (F) on paper without a primer to a score of 2 (C) on paper with the primer, which warrants that it is readable on packaging by a scanner.

High-Quality Images Inkjetted on Different Woven Cotton Fabrics Cationized with P(St-BA-VBT) Copolymer Nanospheres.

The porosity, roughness, and thickness of woven fabrics limit inkjet printing quality, which is extremely important for obtaining high-quality inkjet printing images on fabrics. This study reveals the application of poly[styrene-butyl acrylate-(P-vinylbenzyl trimethyl ammonium chloride)] nanospheres prepared via a soap-free emulsion polymerization approach as a novel kind of the cationization modifier for the inkjet printing of different woven cotton fabrics by the pad-cure process. It was found that the nanospheres exhibited an average diameter of 65.5 nm, a zeta potential of +57.8 mV, and a glass transition temperature of 94.7 °C. The nanospheres deposited on three cotton fabrics through the dip-rolling process, resulting in the increase of zeta potential, hydrophobicity and thickness of the fabric, and the decrease of porosity and roughness. The high-quality inkjet printing images can be obtained on fabrics with different structures owing to the differences in zeta potential, hydrophobicity, porosity, roughness, and thickness of fabrics. The plain, twill, and honeycomb weave fabrics obtained high-quality inkjet printing images for portraits, oil paintings, and landscape paintings, respectively. The nanospheres could strongly adsorb on the fiber by electrostatic attraction. The reactive dye molecules in the inks could react with the cationized fibers by electrostatic attractive force, resulting in the increase of the color strength, fixation rates, and outline sharpness. The nanosphere cationization of different woven fabrics offers a new potential method for obtaining high-quality patterns without significantly affecting the fabric handle.

Fabric Surface Characteristics and their Impact on Digital Textile Printing Quality of PET Fabrics

Pretreatment and yarn type alter the characteristics of fabric surfaces and impact the quality of inkjet digital printing including colorfastness, color shade, colorfulness, and color strength. Specifically, printed pigments are subject to crocking due to physical attachment on a fiber surface without diffusing into the fibers, which increases color transfer to another fabric. This remains a challenge in obtaining high colorfastness as well as full color shade, colorfulness, and color strength. Thus, this study investigated and quantitatively analyzed the effects of pretreatment and yarn type on shade, colorfulness, color strength, and crockfastness. Fabric wettability was also observed to examine the impact on printing quality.

The effect of weave structure on the quality of inkjet polyester printing

In this study, the print quality of lines were investigated in warp and weft directions that were inkjet printed on various weave structures of polyester such as plain, 2/2 twill, 3/1 twill, 3/2 twill and 4/1 twill. In order to study the effect of weave structure on the quality of inkjet printing on polyester fabrics, lines having a width of 1 mm, 2 mm, and 4 mm were inkjet-printed and the print quality was measured as the line width. The quantitative analysis of lines width was performed by scanning the fabrics with a scanner. The obtained result showed that the weave structure is effective on the lines width and print quality, and the plain weave structure had the worst print quality in both directions. Also, the width of lines printed in the weft direction was more than lines printed in the warp direction which is possibly due to more density of warp than weft. The effect of weave structure and print direction on lines width and print quality was also confirmed by the analysis of variance (ANOVA) results. The image processing was shown that the ink spreading shape on the various fabrics is different and is affected by the weave structure and the print direction.

Dynamics of the Remote and Contact Interaction of Liquid Droplets with Film-Like and Fibrous-Porous Polymeric Materials

The problem of inkjet printing quality was considered for the case of synthetic polymer-based film-like and fibrous-porous materials. Physical modeling of inkjet printing on polypropylene using water-based ink revealed remote interaction of liquid droplets with films and nonwoven webs, responsible for the droplet path deviation from the vertical fall and the droplet moving across the polymer film surface after the contact or holding at the fiber ends. Relationships were established and controlling techniques were proposed for the processes of absorption and spreading of liquid droplets in the materials to be printed with the view of increasing the accuracy of printing information symbols and reducing ink consumption.

Inkjet printed large-area flexible circuits: a simple methodology for optimizing the printing quality * * Project supported by the National Key Basic Research Program of China (Nos. 2014CB648300, 2017YFB0404501), the National Natural Science Foundation of China (Nos. 21422402, 21674050), the Natural Science Foundation of Jiangsu Province (Nos. BK20140060, BK20130037, BK20140865, BM2012010), the Program for Jiangsu Specially-Appointed Professors (No. RK030STP15001), the

In this work, a simple methodology was developed to enhance the patterning resolution of inkjet printing, involving process optimization as well as substrate modification and treatment. The line width of the inkjet-printed silver lines was successfully reduced to 1/3 of the original value using this methodology. Large-area flexible circuits with delicate patterns and good morphology were thus fabricated. The resultant flexible circuits showed excellent electrical conductivity as low as 4.5 Ω/□ and strong tolerance to mechanical bending. The simple methodology is also applicable to substrates with various wettability, which suggests a general strategy to enhance the printing quality of inkjet printing for manufacturing high-performance large-area flexible electronics.

The effect of drying behavior of coatings containing pigment and CaCl<sub>2</sub> on inkjet print quality

The effect of drying behavior of coatings containing starch, synthetic silicate pigment and CaCl2 on inkjet print quality was studied. It is known, that print quality is dependent on the ink-substrate interaction, absorption behavior of the substrate and colloidal stability behavior of the ink at the substrate interface. One efficient way of improving the fixation of anionic inkjet pigment colorants is by controlling the electrostatic interaction and colloidal stability by using e.g. divalent or multivalent metal salts. In this study, we have investigated the effect of end moisture content of coating containing hydroxypropylated-starch, synthetic silicate and divalent metal salt (CaCl2) on inkjet print quality of pigment-based ink. It was seen that significant differences in print density could be obtained when using different drying strategies. The obtained effects on substrate-ink interactions were ascribed to changes in coating structure and migration of CaCl2 and better film forming caused by the more intense drying process.

The effect of drying behavior of coatings containing pigment and CaCl<sub>2</sub> on inkjet print quality

The effect of drying behavior of coatings containing pigment and CaCl<sub>2</sub> on inkjet print quality

Aggregation of inkjet ink components by Ca and Mg ions in relation to colorant pigment distribution in paper

Papers coated with salts containing divalent cations exhibit superior inkjet print quality, which has been suggested to be due to fast aggregation of the colorant pigments close to, or even on, the surface of the paper. In this work we show the pivotal role of the carboxylic acid containing dispersing polymer. We report a series of aggregation and sedimentation experiments with commercial inks, generic ink formulations and specific ingredients comprising these formulations, and find differences in their response to the presence of MgCl2 or CaCl2. In particular, flocs and sediments formed in the presence of MgCl2 are denser than those formed in the presence of CaCl2. These differences are not predicted by the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. We suggest that ion specific interactions occurring between Mg2+ or Ca2+, and charged carboxylate groups residing on the dispersing polymers, provoke the observed behavior.