Printing Substrate Research Articles

The effect of electromagnetic radiation on the reflectance spectra of prints on hemp papers

From the moment of production, paper as a printing substrate is exposed to the process of natural ageing regardless of the type of cellulose fibres in its composition. Accordingly, the prints produced by the various printing techniques are also exposed to several factors that impair the quality of the print i.e. its colour over time. Therefore, it is very important to properly select the printing substrate for achieving a high quality of graphic products. For that purpose, three types of papers with hemp fibres were used as printing substrates which were printed with laboratory hand-operated instrument Esiproof using flexographic cyan (C), magenta (M), yellow (Y) and black (K) water-based inks. Prints were artificially aged in SunTEST XLS+ test chamber according to standard ASTM D 6789-02 for 48 and 96 hours. Based on changes in the reflectance spectra of each printed ink after exposure to electromagnetic radiation it was noticed how composition of printing substrate strongly influence on colour stability of prints due time. An increase of exposure time to electromagnetic radiation leads to a decrease in the value of the reflectance of the printing substrate and cyan, magenta and yellow prints. It was confirmed how electromagnetic radiation have the greatest impact on the reflectance of yellow print, while the black one is the most stabile regardless of the substrate it was printed on.

Drying methods of the printing inks

Accelerating the transition to post-print processes needed in the printing industry and shortening the time the product's release time is closely related to the drying time of the ink film. The drying of fluid ink on the surface of the print substrate, transforming from liquid to solid occurs physically and chemically in several ways. Drying systems can be functional alone on the surface of the printing substrate for an ink film or depending on the chemical content of the ink and the properties of the printing substrate, drying can be achieved at the same time with more than one system.Recently, in order to reduce climate, environmental and health impacts and with the development of technology, significant changes are also being experienced in the printing industry and preferences are changing. In this study, more environmentally friendly LED UV and microwave drying systems that save time and energy together with existing basic drying systems such as absorption, evaporation, oxidation-polymerization and conventional UV used in the printing industry are examined. The advantages of different drying systems to the printing industry, preferred drying systems and new studies on this issue have been evaluated.

3D-printing on textiles \u2013 an investigation on adhesion properties of the produced composite materials

The actual paper is related to adhesive properties of 3D objects printed on cotton textile fabrics. For practical applications of 3D prints in the textile sector, the adhesion of the printed object on the textile substrate is an important issue. In the current study, two different types of polymers are printed on cotton – polylactide acid (PLA) and polyamide 6.6 (Nylon). Altogether six cotton fabrics differing in structure, weight and thickness are evaluated. Also, the effect of washing and enzymatic desizing is investigated. For printing parameters, best results are gained for elevated process temperatures, intermediate printing speed and low Z-distance between printing head and substrate. Also, a textile treatment by washing and desizing can improve the adhesion of an afterwards applied 3D print. The presented results are quite useful for future developments of 3D printing applications on textile substrates, e.g. to implement new decorative features or protective functions.

Fabrication of circuits by multi-nozzle electrohydrodynamic inkjet printing for soft wearable electronics

Wearable electronic devices are evolving from current rigid configurations to flexible and ultimately stretchable structures. These emerging systems require soft circuits for connecting the various working units of the overall system. This paper presents fabrication of soft circuits by electrohydrodynamic (EHD) inkjet-printing technique. Multi-nozzle EHD printing head is employed for rapid fabrication of electric circuits on a wide set of materials, including glass substrate (rigid), flexible polyethylene terephthalate (PET) films, and stretchable thermoplastic polyurethane (TPU) films. To avoid the effects of substrate materials on the jettability, the proposed multi-nozzle head is equipped with integrated individual counter electrodes (electrodes are placed above the printing substrate). High-resolution circuits (50 ± 5 µm) with high electrical conductivity (0.6 Ω □−1) on soft substrate materials validate our well-controlled multi-nozzle EHD printing approach. The produced circuits showed excellent flexibility (bending radius ≈ 5 mm radius), high stretchability (strain ≈ 100%), and long-term mechanical stability (500 cycles at 30% strain). The concept is further demonstrated with a soft strain sensor based on a multi-nozzle EHD-printed circuit, employed for monitoring the human motion (finger bending), indicating the potential applications of these circuits in soft wearable electronic devices.Graphic

Determining the optical stability of printed laboratory substrates with wheat pulp after ageing treatment

The use of recovered paper in the paper and board industry worldwide has increased in the last decade. The recycling process affects several properties of the paper, so recovered pulp needs to be enriched with a certain amount of virgin fibre to increase the strength and quality of the paper, and thus the quality of the print. Since the cellulose-based printing substrates are sensitive to photolytic damage caused by exposure to light and high temperature, the focus of the research was to evaluate the stability of digital UV inkjet prints on laboratory substrates with wheat pulp. Assessment of the optical stability of laboratory substrates and prints made on them after ageing treatment was based on the reflectance spectra measurements before and after artificial ageing. In order to observe the optical changes that occur in cellulose printing substrates, unprinted and digital printed substrates were placed in an artificial ageing equipment SunTEST XLS+ test chamber according to standard ASTM D 6789-02. The test chamber emits visible and near ultraviolet electromagnetic radiation in the range from 290 nm to 800 nm. With the deterioration of the optical stability of unprinted and digital printed substrates, it was observed through the reflectance spectra (R) and the Euclidean colour difference (ΔE00*) that the highest colour degradation of all analyzed samples, occurs in the first 48 hours of artificial ageing. The results of this analysis confirm that the addition of wheat pulp in paper pulp provides better optical stability of unprinted and digital printed laboratory substrates.

ПРОБЛЕМЫ РЕКЛАМНЫХ АГЕНСТВ СВЯЗАННЫЕ С ЦВЕТНЫМ ОФОРМЛЕНИЕМ И РЕКОМЕНДАЦИИ ПО ИХ РЕШЕНИЮ

Basılı reklam iletişim sektörünün en önemli araçlarından biridir. Etkili ve doğru kullanıldığı takdirde, geniş kitlelere ulaşmak ve istenilen bilgileri sağlıklı şekilde aktarmak mümkündür. Reklamların görselleştirilmesi sürecine hizmet veren reklam ajansları, müşterilerinin talepleri doğrultusunda bu süreci etkin bir şekilde yönetmeye çalışmaktadırlar. Reklam ajanslarının bu görselleştirme sürecinde karşılaştıkları problemlerin en başında renk kaynaklı problemler gelmektedir. Bu renk kaynaklı problemler reklam ajanları ve müşterileri arasında hukuki boyutlara kadar uzanabilen anlaşmazlıklar çıkarabilmektedir. Bu durum ise reklam ajanslarının prestij, müşteri, zaman ve bunlara bağlı maddi kayıplar yaşamalarına sebep olmaktadır. Bu sebeple reklam ajanslarının renklerle ilgili karşılaşacakları problemleri önceden bilmesi ve önlemler alması gerekmektedir. Fakat bu alanda yeterli kaynak olmaması sektördeki kurumların bilgiye sağlıklı şekilde ulaşmalarında en büyük engeli temsil etmektedir. Bu çalışma ile bu sektöre hizmet veren kurumlara ve bu alanda eğitim veren kurumlara bir kaynak oluşturulması hedeflenmiştir. Bu hedef doğrultusunda yapılan çalışmada reklam ajanslarının basılı reklamların görselleştirilme aşamalarında renk evrenleri, baskı provası alımı, baskı altı malzemesi seçimi, baskı aşaması ve baskı sonrası süreçlerde karşılaşacakları renk problemleri ayrıntılı bir şekilde görsellerle ele alınmış ve nasıl çözecekleri konusunda da önerilerde bulunulmuştur.

Nano‐Ground Glass as a Superhydrophilic Template for Printing High‐Performance Organic Single‐Crystal Thin Films

AbstractThin‐film devices are typically fabricated through a bottom‐up approach, wherein the constituents are deposited sequentially from the bottom to top layer. This method requires the precise management of the heterointerfaces, which leads to complicated integration issues particularly in solution‐processed organic thin‐film transistors (OTFTs). This limitation arises because a surface suitable for the printing of semiconductors is not necessarily suitable for maximizing the electronic properties of OTFTs. To overcome this, a transfer technique of organic semiconductor (OSC) thin films has been studied. This enables facile transfer of the OSC thin film from a hydrophilic template to any given substrate; thus, the printing substrate and destination substrate can be optimized individually. Here, a nano‐ground glass (NGG) is developed whose surface is chemically etched using a mild base. The NGG functions as a thermally stable, superhydrophilic template for printing high‐quality single‐crystal OSC thin films. To evaluate the practical applicability of the NGG, an n‐type OSC, which requires a relatively high temperature of around 150 °C during crystal growth, is fabricated. The fabricated OTFTs exhibit an outstanding electron mobility of 2.2 cm2 V−1 s−1. The NGG proposed in this study can be utilized for the fabrication of a wide variety of printable materials.

Silver Inkjet-Printed Electrode on Paper for Electrochemical Sensing of Paraquat

The use of fully printed electrochemical devices has gained more attention for the monitoring of clinical, food, and environmental analytes due to their low cost, great reproducibility, and versatility characteristics, serving as an important technology for commercial application. Therefore, a paper-based inkjet-printed electrochemical system is proposed as a cost-effective analytical detection tool for paraquat. Chromatographic paper was used as the printing substrate due its sustainable and disposable characteristics, and an inkjet-printing system deposited the conductive silver ink with no further modification on the paper surface, providing a three-electrode system. The printed electrodes were characterized with scanning electron microscopy, cyclic voltammetry, and chronopotentiometry. The proposed sensor exhibited a large surface area, providing a powerful tool for paraquat detection due to its higher analytical signal. For the detection of paraquat, square-wave voltammetry was used, and the results showed a linear response range of 3.0–100 μM and a detection limit of 0.80 µM, along with the high repeatability and disposability of the sensor. The prepared sensors were also sufficiently selective against interference, and high accuracy (recovery range = 96.7–113%) was obtained when applied to samples (water, human serum, and orange juice), showing the promising applicability of fully printed electrodes for electrochemical monitoring.

Fabrication of screen-printed electrodes: opportunities and challenges

In recent times, wearable electronics, real-time sensing devices and point-of-care device applications have seen a surge in demand. This demand inherently calls for a more economic and reliable method of mass production. One such robust technique is screen printing that offers advantages in terms of being versatile, economical and easy to use. This technique has been proclaimed to be the best amongst the other additive manufacturing techniques by many research groups. This can be solely attributed to its simple equipment design, requiring a paste for printing purpose, a meshwork for housing the design and a squeegee to carry out printing through an up-and-down motion. This subsequently calls for optimising the parameters such as ink rheology, pore size of the mesh, proper choice of mesh design and motion of the squeeze in order to fabricate electrodes for desired purpose. Due to this technique’s immense potential to open up broad inroads in the domain of flexible electronics, whose concept has radically redefined the perception towards the field of electronics, a review article encompassing an elaborate description on the science and other quintessential parameters involved in this mass printing technique would prove to be extremely useful. In this purview, the review article is compartmentalised into sections encompassing discussion on the manufacturing of different kinds of inks for screen printing applications, substrates used, electrode design and pre-treatment procedures.

The effect Ecofriendly Super hydrophobic Nano composites Coating and Penetration of Printing Inks on Paperboard Packaging Materials

The packaging industry is one of the pioneering industries facing many challenges during the production cycle. Migration of printing ink in packing items is the harmful problem for customer, Therefore, this study aims to reduce the penetration of ink into the product, one of the unavailable technologies is coating printing substrates with a polymer layer. Ecofriendly Super hydrophobic coating was prepared in aqueous medium based on silicon dioxide and characterized with particle size analyzer Dynamic laser scattering )DLS( and zeta potential. Paper duplex 180 g/m2 were coated with prepared superhydrophobic Nano coating through spray coating with emulsion solution. The coated paper sheets were printed by lithooffist and testes by X-rite instrument. This polymer can seal the pores of the printing materials. It is also a barrier to prevent the leakage and deportation of ink particles into the packaging that can occur in various raw materials, especially untreated materials as well as. One of the advantages of this polymer is to reduce the penetration of ink consumed for printing, that is, it is of double benefit, which is protection and reduce ink penetration, and the research results show the effective use of this polymer layer, whether in roughness, water absorption, Ink penetration and printing properties

Nanoparticle Exposure and Workplace Measurements During Processes Related to 3D Printing of a Metal Object.

Metal 3D printing has many potential uses within prototyping and manufacturing. Selective laser melting (SLM) is a process that uses metal powders in the micrometer range as printing material. The particle release from the entire SLM printing process is not well-studied. While the 3D printing itself often occurs in a sealed chamber, activities related to the process can potentially release harmful metal particles to the indoor working environment through resuspension of the printing powder or via incident nanoparticles generated during printing. The objective of this study was to improve the understanding of particle exposure in work processes associated with 3D printing and potential needs for interventions by a case study conducted in a 3D printing facility. In this setting, direct release and dispersion of particles throughout the workspace from processes related to metal 3D printing was investigated. The release from five activities were studied in detail. The activities included post-printing cleaning, object annealing, and preparation of new base substrate for the next printing was. Three of the five measured activities caused particles number concentrations in the working environment to increase above background levels which were found to be 8·102 cm−3. Concentrations during chamber emptying and the open powder removal system (PRS) cleaning processes increased to 104 and 5·103 cm−3, respectively, whereas grinding activity increased number concentrations to 2.5·105 cm−3. Size distributions showed that particles were mainly smaller than 200 nm. Respirable mass concentrations were 50.4 μg m−3, collected on filters. This was corroborated by respirable mass measured with a DustTrak of 58.4 μg m−3. Respirable mass concentrations were below the occupational exposure limits in Denmark for an 8 h time-weighted average.

Description of Thermochromic Offset Prints Morphologies Depending on Printing Substrate

In this study, the influence of physio-chemical properties of four printing substrates, fibrous papers (filter, bulky, recycled), and polymer film (synthetic paper) on the size of the thermochromic (TC) prints microcapsules was investigated. Results indicate that interaction between thermochromic ink and printing substrate determine the print morphology, i.e., porosity and roughness of printing substrate affect dimensions of TC microcapsules of resulting prints, while ink adhesion affects dimensional changes during heating–cooling cycle. Atomic force microscopy (AFM) analysis showed that microcapsules of the prints, on the surface of the smoothest synthetic paper, possess the smallest diameter and height, while, on the most porous and the most roughened surface of F paper, the microcapsules of the prints possess the highest diameter and height. By increasing the temperature to 40 °C, the biggest changes in the shape of the microcapsules (increase in height and decrease in diameter) were obtained using the surface of the hydrophilic filter paper. While using the recycled paper surface, the situation is opposite; the height and diameter of the microcapsules are reduced, and the microcapsules penetrate deeper into the paper structure (due to optimum adhesion). On the bulky paper surfaces, which are more hydrophobic than recycled paper (higher interfacial tension), the increase of temperature does not cause any significant changes in the shape and position of the microcapsules. The same behavior is observed using hydrophobic non-porous synthetic paper.

3D printing of syntactic foam cored sandwich composite

In additive manufacturing, fused filament fabrication (FFF) based three-dimensional printing (3DP) is one of the most popular rapid processing technologies. The key benefit of 3DP is the ability to build integrated, complex, and tailored components. Optimization of feedstock material and associated 3DP process to achieve the required properties for various applications has been an important research field in the recent past. The main objective of this paper is 3DP of syntactic foam cored sandwich composite all at once (skin-core-skin printing in sequence at once). High density polyethylene (HDPE) and glass microballoon (GMB) reinforced (20, 40, and 60 by volume%) HDPE blends are fed into the extruder for manufacturing respective filaments. These HDPE and HDPE/GMB filaments are further sent to the FFF based printer to realize skin and syntactic foam core respectively of the sandwich. The selection of substrate for printing and the crucial issues associated with the printing of core and sandwich composites are analyzed. The present work successfully demonstrates that by optimizing the printing parameters, good quality core and sandwich structures can be printed all at once without any defects. Finally, the suitable printing parameters are used as boundary conditions in finite element (FE) simulation of sandwich for carrying out thermomechanical analysis to analyze the thermal stress distributions in the prints.

Surface analysis of polymer films for wettability and ink adhesion

AbstractThe interaction between inks and substrates is critical during printing. Adhesion of the ink film is determined by the reciprocal interactions of polar and nonpolar (dispersive) components between polymer films and inks. The greater the similarity between the polar and dispersive components of inks, coating and substrates, the better the wetting and adhesion on the surface of printing substrate. Various liquid materials in printing such as inks, varnishes, lacquers, and adhesives contain high ratios of water. The highly polar nature of water makes the interaction of these materials unsuitable with predominantly disperse polymer surfaces. Some films with polyolefin structure, especially polypropylene, and polyethylene, are nonpolar and cannot form strong bonds with ink, varnish, or lacquer coatings due to their chemical structure. Increasing surface energy components overcomes the poor wetting and adhesion on polymer surfaces. In this review, the topics of water contact angle measurement and determination of surface energy, surface tension, and using sessile drop method for the wettability and ink adhesion of polymer films are surveyed. Information on structural and chemical processes was given that assists in obtaining wettable film surfaces. Recommendations were made for good adhesion and printability based on surface treatment methods and ink modification.

Influence of Some Flexographic Printing Process Conditions on the Optical Density and Tonal Value Increase of Overprinted Plastic Films

The print quality of prints performed with flexographic printing technology is influenced by various parameters such as viscosity of the printing inks, printing substrates, plates, anilox rolls, etc. The aim of this work is to analyze the influence of ink viscosity, printing plate and printing base on selected properties of print quality, such as optical density of full tone area and the increase of tonal value (TVI). Additionally, the printed dots on 5, 15, 30, 50 and 75% of half tone area were investigated using digital microscopy. The least square fitting method in a matrix form was successfully used in order to confirm the influence of printing process parameters on print quality. The results obtained reveal the significant influence of the printing plate and printing substrate characteristics and the lesser influence of printing ink viscosity for 40–100% coverage area. The values of the optical densities of full tone areas are mainly influenced by the properties of the printing plate and the printing base. Furthermore, the optical density decreases when the value of flow time decreases, which is related to the lower thickness of dried ink film. The TVI on light tones (0 to 20%) is mainly influenced by the ink viscosity.

3D printing of semicrystalline polypropylene: towards eliminating warpage of printed objects

Fused filament fabrication (FFF) is an extrusion-based 3D printing technique for thermoplastic polymers. In this technique, molten polymer is extruded through a print nozzle and is laid down layer by layer to build up the printed object. Currently, FFF is used primarily to print amorphous or low-crystallinity polymers, such as acrylonitrile butadiene styrene copolymer (ABS) or polylactic acid (PLA). Printing of semicrystalline polymers, such as polyethylene or polypropylene remains particularly challenging. During FFF of semicrystalline polymers, large thermomechanical stresses are generated when the polymer solidifies on cooling. These stresses result in warpage of the printed part. Here, we analyse the factors that influence stresses generated during FFF 3D printing of a commercial semicrystalline polymer, isotactic polypropylene. We investigate the effect of height of the printed object on part warpage, as well the effect of infilling during printing. We demonstrate that the stresses generated during FFF can be substantially decreased by incorporation of a ‘brim’, viz. a thin layer at the base of the printed object, and by adhering the brim to the print substrate using common polyvinyl acetate-based glue. We systematically investigate the effect of the brim size on the warpage of the printed object. We support our experimental findings with finite element method (FEM) simulations that explain the mechanism of stress buildup during printing. The trend in stresses calculated in the FEM simulations parallel the warpage measured in the experiments. Thus, this work represents an important methodological advance towards warpage-free FFF printing of semicrystalline polymers.

Organic transistors based on oxidized single-walled carbon nanotube electrodes patterned via simple spray coating

We developed a facile spray-printing method to fabricate oxidized single-walled carbon nanotube (Oxy-SWCNT) source-drain electrodes for use in organic field-effect transistors (OFETs). Surface oxidized SWCNT bundles enables the solution processability of Oxy-SWCNT without dispersant. The spray printing of an Oxy-SWCNT solution via a shadow mask led to electrode patterns with excellent transparency and electrical conductivity. Pattern resolution was optimized by adjusting printing volume and substrate temperature. The performance of the pentacene FETs with Oxy-SWCNT electrodes was compared with that of conventional Au electrodes. The FETs with Oxy-SWCNT electrodes exhibited higher charge carrier mobilities, on/off current ratios, and optical transmittances than those of FETs with Au electrodes. The increased device performance of the FETs with Oxy-SWCNT electrodes is due to the low contact resistance resulting from the efficient charge injection and transport across the electrode-channel interface. High work function (−5.1 eV) of the Oxy-SWCNT facilitated the charge injection. Our study demonstrates that Oxy-SWCNTs exhibit exceptional potential as a printable electrode material for OFETs and promise a better replacement for electrodes in transparent and flexible electronics.

Subterahertz refractive flat-top beam shaping via 3D printed aspheric lens combination

The viability of 3D printed aspheric lenses for the purpose of frequency-scalable subterahertz Gaussian to flat-top beam shaping is evaluated. A cylindrical one-dimensional Fresnel–Kirchhoff diffraction equation was implemented in Matlab and used to design a pair of aspheric lenses with customized vertex radius of curvature and conic constant. The lenses were printed at maximum possible resolution in acrylonitrile butadiene styrene ( n = 1.6 ) and tested with a 102 GHz continuous-wave subterahertz source. The aspheric lens combination produced a flat-top profile from a low-quality incident Gaussian beam at the minimal cost of 3D printing substrate. The flat-top profile exhibited small ( < 14 % root-mean-square deviation over a flat region) intensity fluctuations and is expected to prove useful in future terahertz applications that require a high degree of beam uniformity.

The Possibility of Increasing the Achromatic Tone Values of FOGRA 51 Standards Achieved by the Modification of in Line Pre-Treatment of the Printing Substrate

The Possibility of Increasing the Achromatic Tone Values of FOGRA 51 Standards Achieved by the Modification of in Line Pre-Treatment of the Printing Substrate

Penetrating glassy carbon neural electrode arrays for brain-machine interfaces.

This paper presents a fabrication method for glassy carbon neural electrode arrays that combines 3D printing and chemical pyrolysis technology. The carbon electrodes have excellent biological compatibility and can be used in neural signal recording. A pretreated Si wafer is used as the substrate for 3D printing, and then, stereolithography 3D printing technology is employed to print photosensitive resin into a cone shape. Next, chemical pyrolysis is applied to convert the 3D prints into glassy carbon electrodes and modify the electrochemical performance of the carbon electrodes. Finally, the glassy carbon electrodes are packed with conductive wires and PDMS. The proposed fabrication method simplifies the manufacturing process of carbon materials, and electrodes can be fabricated without the need of deep reactive ion etching (DRIE). The height of the carbon electrodes is 1.5mm, and the exposure area of the tips is 0.78mm2, which is convenient for the implantation procedure. The specific capacitance of the glassy carbon arrays is higher than that of a platinum electrode (9.18 mF/cm2 vs 3.32 mF/cm2, respectively), and the impedance at 1kHz is lower (7.1 kΩ vs 8.8 kΩ). The carbon electrodes were tested in vivo, and they showed excellent performance in neural signal recording. The signal-to-noise ratio of the carbon electrodes is 50.73 ± 6.11, which is higher than that of the Pt electrode (20.15 ± 5.32) under the same testing conditions. The proposed fabrication method of glassy carbon electrodes provides a novel approach to manufacture penetrating electrodes for nerve interfaces in biomedical engineering and microelectromechanical systems.