Curable Ink Research Articles

Tuning of ultraviolet‐curable ink printability via in situ ultraviolet irradiation during direct ink write applications

AbstractDirect ink write deposition facilitates line‐by‐line extrusion of inks spanning wide viscoelastic ranges. Following deposition, post processing technologies permit tuning of the extrudate's material property characteristics—ultraviolet (UV) irradiation, facilitating the photopolymerization of UV‐reactive catalyst solutions, permits targeted modification of the extrudate's microstructure and in situ tuning of extrudate macrostructure. This report analyzes the morphological, rheological, and microstructural property relationships governing the printability, and processivity, of extruded UV‐curable resin inks for delineation of sufficiency and optimization of ink printability utilizing direct ink write technologies. A design‐of‐experiments approach is implemented to quantify significance regarding an extrudate's dimensional response to extrusion parameter variation and in situ processing parameters, identifying proportionally of nozzle velocity, nozzle height, and UV irradiation exposure with extrudate aspect ratio, reflected by respective maximum extrudate aspect ratio increases of 158% and 109%, regarding 121 and 123K resin inks. Finally, the relationship between extrudate morphology and microstructure variation was assessed via dielectric cure monitoring, whereby an extrudate's ion viscosity was calculated in relation to its rheological modulus, reflecting the relationship between an extrudate's morphology, rheological response, and printability, regarding its microstructural variation.

Preparation and wear resistance of water-based UV curable ink

ABSTRACT UV water-based inks have disadvantages such as slow curing speed and low degree of crosslinking. In this paper, the copolymer P(MMA-r-HEMA) was prepared by traditional free radical polymerization using methyl methacrylate (MMA) and hydroxyethyl methacrylate (HEMA) as monomers, and the copolymer P(MMA-r-HEMA) was modified by acrylic acid (AA) to synthesis completely water-soluble acrylic prepolymer P(MMA-r-HEMA)-g-AA. Triethylenetetramine reacted with glycidyl methacrylate (GMA) to yield a multifunctional reactive diluent TGMA. Secondly, acrylic prepolymer P(MMA-r-HEMA)-g-AA, multifunctional reactive diluent TGMA and photoinitiator were used to prepare water-based UV curable ink. The influence of the type and quality of photoinitiator, the relative molecular weight and mass fraction of P(MMA-r-HEMA)-g-AA, the number of functional groups and mass fraction of TGMA on the UV ink curing speed and the wear resistance of the ink film were discussed. When the mass fraction of the photoinitiator TPO was 1%, the number-average relative molecular mass of the prepolymer was 1.67 × 104 g/mol and the mass fraction was 60%, the number of functional groups of the reactive diluent was 6 and the mass fraction was 40%, the light curing of UV water-based ink was completed in 0.1 s, and the mass loss after 50 times abrasion was 0.2–0.4%.

Evaluation of Ultraviolet Radiation using the MOORA Method

Ultraviolet Radiation. Non-ionizing radiation emitting manmade sources like the sun and tanning beds includes ultraviolet (UV) radiation. Although it can help humans produce vitamin D and has other advantages, it can also be harmful to their health. The sun is a natural source of UV radiation for us. In industrial processes, as well as in medical and dental procedures, ultraviolet light is frequently used for a variety of purposes, such as the destruction of bacteria, the production of fluorescent effects, the curing of inks and resins, phototherapy, and tanning. Different UV wavelengths and intensities are employed for diverse applications. Using a UV detector is the most secure method of detecting UV radiation. Inform the class that the beads they will be using contain a unique pigment that changes color when exposed to UV radiation. UV detectors are the name of these beads. The UV light around the school can be seen using these. UV radiation is necessary to the body because it promotes the production of vitamin D. In addition to being crucial for bone development, immune system health, and blood cell production, vitamin D increases the absorption of calcium and phosphorus from meals. The three key health benefits of UV light are vitamin D production, enhanced mood, and higher energy. Moderate UV light exposure is a good source of vitamin D. This vitamin helps regulate cell division, insulin synthesis, calcium metabolism, immunity, and blood pressure. History and exploration. Due to violet being the color of the highest frequencies of visible light, the word "ultraviolet" signifies "beyond violet" (Latin ultra, "beyond"). Compared to violet light, ultraviolet has a greater frequency and a shorter wavelength. UV radiation can produce erythema, sunburn, photodamage (photoaging), photosensitivity, eye damage, changes in the skin's immune system, and chemical hypersensitivity depending on the amount and kind of radiation and the type of skin of the individual exposed. -an s-in-the-service-retailer-in-reside-in-the-retail-d-in-star-re-in-main-retail-enterprise type of place. This one. Additionally, UV radiation is produced by sunlamps and tanning beds. The multi-objective optimization by ratio analysis (MOORA) method is one of the MADM techniques. It is a group of qualities (prospective students). It is possible to calculate the worth of criteria, making this the ideal choice for decision-makers like prospective students. Hospital inpatient care, Hospital ambulatory care, Primary health care, Pharmaceuticals, Mortality, Morbidity. Cutaneous Melanoma, Basal Cell Carcinoma, Melanoma in Situ, and Actinic Keratosis. From the result, it is seen that Morbidity got the first rank whereas Primary health care is having the lowest rank.

Direct Write Printing of Ultraviolet-Curable Bulk Superhydrophobic Ink Material.

Although superhydrophobic surfaces have various promising applications, their fabrication methods are often limited to 2D plane surfaces that are vulnerable to abrasion and have limited adhesion to the substrate. Herein, an ultraviolet (UV) curable ink with bulk superhydrophobicity, consisting of poly(dimethylsiloxane) (PDMS) resins, hydrophobic silica, and solvent (porogen), was successfully developed for UV-assisted direct write printing processing. After UV curing of the ink followed by solvent evaporation, the generated porous structure cooperates with silica particles to form a self-similar and hierarchical structure throughout the bulk material, which can keep its original morphology even after cyclic abrasion (over 1000 times) and thus exhibits durable superhydrophobicity. With this unique ink, UV-assisted direct write printing can not only create 2D superhydrophobic surfaces on various substrates (e.g., paper and wire mesh) but also fabricate self-supporting 3D superhydrophobic objects for various applications such as waterproofing and oil-water separation. The printed objects exhibited a stable superhydrophobicity against liquid corrosion and mechanical damage. In addition, the 3D printing approach can be used to optimize the oil-water separation performance of the superhydrophobic porous materials by tuning the pore size, thus presenting promising applications.

Improved fatigue resistance in transfer-printed flexible circuits embedded in polymer substrates with low melting temperatures

Flexible electronics are of great interest and importance due to their applications in a range of fields, from wearable electronics to solar cells. Whilst resolutions of printed flexible electronics have been improving in recent years, there remain problems with mechanical fatigue and substrate cost, curtailing the use of such devices and resulting in increased cost and waste products. Here we present a novel method for improving the fatigue resistance of printed flexible electronics by a factor of ∼40 by sintering the electronics prior to transferring them into low-cost polymer substrates, such that they remain embedded. This method is demonstrated using circuits printed using silver nanoparticulate ink with an aerosol jet printer, and could be applicable to multiple different metallic inks. At the same time, this method can be used to transfer print circuits into polymers with low melting temperatures, without the need for otherwise detrimentally high sintering temperatures required for ink curing.

14.4: Inkjet Printing Patterned Quantum Dot Microarrays

14.4: Inkjet Printing Patterned Quantum Dot Microarrays

Gamma Radiation Processed Polymeric Materials for High Performance Applications: A Review.

The polymeric properties are tailored and enhanced by high energy radiation processing, which is an effective technique to tune the physical, chemical, thermal, surface, and structural properties of the various thermoplastic and elastomeric polymeric components. The gamma and electron beam radiation are the most frequent radiation techniques used for crosslinking, compatibilizing, and grafting of various polymer blends and composites systems. The gamma radiation-induced grafting and crosslinking are the effective, rapid, clean, user-friendly, and well-controlled techniques for the polymeric materials for their properties improvement for high performance applications such as nuclear, automobile, electrical insulation, ink curing, surface modification, food packaging, medical, sterilization, and health-care in a different environment. Similarly, electron beam radiations crosslinking has been a well-known technique for properties development and has economic benefits over chemical crosslinking techniques. This review focuses on the development of polymeric multi component systems (functionalized polymer, blends, and nanohybrids), where partially nanoscale clay incorporation can achieve the desired properties, and partially by controlled high energy radiations crosslinking of blends and nanocomposites. In this review, various investigations have been studied on the development and modifications of polymeric systems, and controlled dose gamma radiation processed the polymer blends and clay-induced composites. Radiation induced grafting of the various monomers on the polymer backbone has been focused. Similarly, comparative studies of gamma and electron beam radiation and their effect on property devlopment have been focused. The high energy radiation modified polymers have been used in several high performance sectors, including automotive, wire and cable insulation, heat shrinkable tube, sterilization, biomedical, nuclear and space applications.

Application of ATR-IR measurements to predict the deinking efficiency of UV-cured inks

In recent years, ultraviolet (UV)-curable ink has been developed and widely used in various printing applications. However, using UV-printed products (UV prints) in recovered paper recycling causes end-product dirt specks and quality issues. A new method was developed that can distinguish UV prints from other prints by means of attenuated total reflectance infrared (ATR-IR) spectroscopy. Application of this method could allow more efficient use of UV prints as raw materials for paper recycling. First, a mill trial was performed using UV prints alone as raw materials in a deinked pulp (DIP) process. Second, test prints were made with four types of UV inks: a conventional UV ink and three different highly-sensitive UV inks. Each print sample had four levels of four-color ink coverage patterns (100%, 75%, 50%, and 25%). Next, drinkability of all prints was evaluated by laboratory experiments. Finally, each print was measured using the ATR-IR method, and the relationship between the IR spectra and deinkability was investigated. Mill trial results showed that UV prints caused more than 20 times as many dirt specks as those printed with conventional oil-based ink. There were variations in recycling performance among UV prints taken from bales used for the mill trial. Lab tests clearly revealed that not all UV-printed products lead to dirt specks. In order to clarify the factors that affected deinkability of UV prints, the print samples were investigated by lab experiments. Key findings from lab experiments include: • The number of dirt specks larger than 250 μm in diameter increased as the ink coverage increased. • Higher ink coverage area showed stronger intensity of ATR-IR spectral bands associated with inks. These results indicate that deinkability of UV prints could be predicted by analysis of ATR-IR spectra. • Finally, the method was applied for assessment of recovered paper from commercial printing presses. It was confirmed that this method made it possible to distinguish easily deinkable UV prints from other UV prints. Based on these findings, we concluded that the ATR-IR method is applicable for inspection of incoming recovered paper.

Influence of procedural noise on the glossiness of 2.5D printed patches

Perlin noise, a type of procedural noise, was used for the design of elevation files for 2.5D printing. This printing method uses elevation data from a height map to create physical relief by superimposing layers of ink. In this experiment, the grayscale values of noise functions were used as elevation values to build different surface structures in UV curable ink by 2.5D printing. Printed samples with varying levels of Perlin noise were created and their reflectance properties were studied by measuring the values of specular gloss. The roughness and specular gloss of the printed surfaces were effectively influenced when varying the persistence and octaves of the noise functions. The aim of implementing the procedural approach to a high-resolution printing method has been to explore the reflectance properties of custom noise functions when transferred to the physical realm. This might contribute to better understand the effect of surface structure on the appearance of materials. Potentially, this approach will enable the use of relief printing to produce structures with a more natural appearance and a desired gloss value by using a low-cost computing process.

Influence of Ink Curing in UV LED Inkjet Printing on Colour Differences, Ink Bleeding and Abrasion Resistance of Prints on Textile

Digital printing techniques are increasingly present in the field of textile printing. Particularly prominent is the inkjet printing technique using water-based inks, UV LED inkjet printing also increasingly being in use. UV LED inkjet is primarily not intended for direct clothing printing; however, it can be used especially as a hybrid solution in the soft signage market. It is a great option for the printers that are not engaged only in textile printing, and want a more versatile print portfolio, extending it to non-clothing textile products, e.g. soft signage and non-wearable products. As these types of products often require colour reproduction of logos, accurate colour reproduction, good ink adhesion and sharpness are important just like in other printing technologies. In order to evaluate the impact of UV LED radiation amount on colour differences, ink bleeding and abrasion resistance, six different fabric samples (five woven and one nonwoven) were printed using a UV LED inkjet printer. Based on the results of colour difference, it was established that a reduction of UV radiation (by half the manufacturer’s recommended amount) had no effect on this parameter. However, perceptible colour differences were observed with the use of different M measurement conditions defined by the international standard ISO 13655-2017. Reducing the amount of UV radiation had no effect on the adhesion and durability of the printed ink. Small differences detected in these two parameters were mainly a consequence of the properties of textile materials and not of decreased UV radiation.

Current capabilities of prototyping technologies for multilayer printed circuit boards on a 3D printer

A new direction in 3D printing was investigated – prototyping of single-sided, double-sided and multilayer printed circuit boards. The current capabilities and limitations of 3D printed circuit board printing technology were identified. A comparative analysis of the characteristics of two desktop 3D printers presented in the industry for prototyping radio electronics, as well as the first professional machine DragonFly LDM 2020, which is a mini-factory for prototyping multilayer printed circuit boards, was carried out. The first practical experience of working and printing on DragonFly LDM 2020 supplied to the megalaboratory “3D prototyping and control of multilayer printed circuit boards” of the Institute of Radio Engineering and Telecommunication Systems MIREA – Russian Technological University is presented. The first samples of electronic boards printed on a 3D printer by the method of inkjet printing were obtained. An additive technology for the production of multilayer printed circuit boards is considered: printing with two printheads with conductive and dielectric nano-ink with two curing systems: an infrared sintering system for conductive ink and a UV curing system for dielectric ink. The LDM (Dragonfly Lights-out Digital Manufacturing) production method with the necessary maintenance is presented. The method allows the system to work roundthe-clock with minimal human intervention, significantly increasing the productivity of 3D printing and expanding the possibilities of prototyping. The materials used for 3D printing of multilayer printed circuit boards and their characteristics were investigated: dielectric acrylate nano-ink (Dielectric Ink 1092 – Dielectric UV Curable Acrylates Ink), conducting ink with silver nanoparticles (AgCite™ 90072 Silver Nanoparticle Conductive Ink). The research carried out allows us to compare the technological standards of printed electronics with traditional methods of manufacturing multilayer printed circuit boards for a number of parameters.

An Improved Model of Height Profile for Drop-On-Demand Print of Ultraviolet Curable Ink

Abstract This paper proposes an improved model of height profile for drop-on-demand printing of ultraviolet curable ink. Unlike previous model, the proposed model propagates volume and covered area based on height difference between adjacent drops. Height profile is then calculated from the propagated volume and area. Measurements of two-drop and three-drop patterns are used to experimentally compute model parameters. The parameters are used to predict and validate height profiles of four and more drops in a straight line. Using the same root-mean-square (RMS) error as benchmark, this model achieves 5.9% RMS height profile error on four-drop lines. This represents more than 60% reduction from graph-based model and an improvement from our previous effort.

3D Printing Low-Stiffness Silicone Within a Curable Support Matrix.

Embedded 3D printing processes involve extruding ink within a support matrix that supports the ink throughout printing and curing. In once class of embedded 3D printing, which we refer to as "removable embedded 3D printing," curable inks are printed, cured, then removed from the uncured support matrix. Removable embedded 3D printing is advantageous because low-viscosity inks can be patterned in freeform geometries which may not be feasible to create via casting and other printing processes. When printing solid-infill geometries, however, uncured support matrix becomes trapped within the prints, which may be undesirable. This study builds on previous work by formulating a support matrix for removable embedded 3D printing that cures when mixed with the printed silicone ink to solve the problem of trapped, uncured support matrix within solid-infill prints. Printed specimens are shown to have a nearly isotropic elastic modulus in directions perpendicular and parallel to the printed layers, and a decreased modulus and increased elongation at break compared to specimens cast from the ink. The rheological properties of the support matrix are reported. The capabilities of the printer and support matrix are demonstrated by printing a variety of geometries from four UV and addition-cure silicone inks. Shapes printed with these inks range by nearly two orders of magnitude in stiffness and have failure strains between approximately 50 and 250%, suggesting a wide range of potential applications for this printing process.

Development of Ultraviolet Curable Ink with Wide Gamut and High Adhesion

Development of Ultraviolet Curable Ink with Wide Gamut and High Adhesion

Cytotoxic effects of thioxanthone derivatives as photoinitiators on isolated rat hepatocytes.

Thioxanthone and its analogues, 2- or 4-isopropylthioxanthone, 2-chlorothioxanthone, 2,4-diethylthioxanthone (DETX) and xanthone, are used as photoinitiators of ultraviolet (UV) light-initiated curable inks. As these photoinitiators were found in numerous food/beverage products packaged in cartons printed with UV-cured inks, the cytotoxic effects and mechanisms of these compounds were studied in freshly isolated rat hepatocytes. The toxicity of DETX was greater than that of other compounds. DETX elicited not only concentration (0-2.0 mm)- and time (0-3 hours)-dependent cell death accompanied by the depletion of cellular adenosine triphosphate (ATP), and reduced glutathione (GSH) and protein thiol levels, but also the accumulation of GSH disulfide and malondialdehyde. Pretreatment of hepatocytes with either fructose at a concentration of 10 mm or N-acetyl-l-cysteine (NAC) at a concentration of 5.0 mm ameliorated DETX (1 mm)-induced cytotoxicity. Further, the exposure of hepatocytes to DETX resulted in the induction of reactive oxygen species (ROS) and loss of mitochondrial membrane potential, both of which were partially prevented by the addition of NAC. These results indicate that: (1) DETX-induced cytotoxicity is linked to mitochondrial failure and depletion of cellular GSH; (2) insufficient cellular ATP levels derived from mitochondrial dysfunction were, at least in part, ameliorated by the addition of fructose; and (3) GSH loss and/or ROS formation was prevented by NAC. Taken collectively, these results suggest that the onset of toxic effects caused by DETX may be partially attributable to cellular energy stress as well as oxidative stress.

Design of arrayed multi-wavelength UVLED ink curing system

Compared with mercury-vapor lamp, ultraviolet (UV) LED suffers from the disadvantage of having a single wavelength, which is not fully compatible with the existing photoinitiator of ultraviolet ink. It is difficult using UVLEDs to achieve the curing effect comparable to what mercury-vapor lamp can do. This article presents a design of UVLED ink curing system that provides evenly mixed light with multiple wavelengths. We put a UVLED array with three wavelengths on a cambered surface and achieved uniform illumination in ink curing area by using optical freeform surface. By adding the adjusting of the tilt angle, we solved the dilemma of uniform wavelength mixing and uniform illumination. The ray tracing simulation results show that an illumination spot with uniform wavelength mixing, an average illumination of 110.7 mW/cm2, and an illuminance uniformity of 0.82 is obtained on a target surface 600 mm away from the light source. This design is expected to simulate the multi-spectral illumination effect of mercury-vapor lamps, which can promote the application of UVLEDs in ink curing.

Printing and curing of conductive inks on fabric using syringe-based deposition system and oven for wearable antenna application

Wearable antenna is part of clothing for transmitting or receiving wireless signals and due to miniaturization, the antenna required to be compact, light, cheap and almost maintenance-free. Syringe-based deposition system with conductive ink is potential to print the antenna structure on fabric as it provides flexibility and compatible with different viscosity of materials. The study is to investigate the printing and curing of conductive inks on fabric using syringe-based deposition system and oven. The effect of printing and curing parameters to morphology and conductivity of the antenna tracks were investigated. Several mechanical and electrical tests were performed to determine the hardness, adhesion and resistance level. It was observed that the antenna tracks were successfully printed according to its designated shape and printing with higher speed caused narrower antenna ink track while pressure differences influenced the thickness of the antenna tracks. The optimum printing parameters obtained was printing at 23 mm/s speed with a pressure of 1 bar to achieve the required antenna track size. The resistance level achieved was considered low at 1.6Ω curing at 160°C for 45 minutes. It was proven that the syringe-based deposition system and oven is capable of printing and curing antenna tracks on fabric.

Development of Highly Energy Densified Ink for 3D Printable Batteries

AbstractNovel Li‐ion battery inks are integral elements to increase mechanical integrity and energy density of 3D printable batteries. Conventional battery inks have been limited to the Polyvinylidene fluoride (PVdF) and N‐methyl‐2 pyrrolidon (NMP) solvent that are unpleasant of long drying process and environmentally hazard solvent. As a novel Li‐ion battery ink for highly energy densified 3D printable batteries, we have developed acrylate‐based curable inks which demonstrate fast process, highly cross‐linked polymerization and more eco‐friend suspension. Here, we report a novel development of curable LIB ink with fundamental studies of rheology, curing behavior and electrochemical performances. The viscosity and activation energy of curable LIB inks are low and shear shinning behavior and 118.9 kJ/mol, respectively, which are appropriate for the extrusion 3D printer with nozzle radius of 0.75 mm and the speed of 5 mm/sec. Furthermore, electrochemical performance of capacity, oxidation peak and cycle retention is comparable to conventionally fabricated electrode.

Photonic Curing of Low-Cost Aqueous Silver Flake Inks for Printed Conductors with Increased Yield.

Printing of highly conductive tracks at low cost is of primary importance for the emerging field of flexible, plastic, and large-area electronics. Commonly, this is achieved by printing of metallic conductive inks, often based on Ag or Cu nanoparticles dispersed in organic solvents. The solvents, which must be safely removed, have particular storage and handling requirements, thus increasing the process costs. By using water-based inks containing micron-sized silver flakes, both material and process costs can be reduced, making these inks attractive for industrial applications. However, the sintering of flake inks requires higher temperatures than nano-sized inks owing to the particles' smaller surface area-to-volume ratio, meaning that when cured thermally the conductivity of many flake inks is lower than nanoparticle alternatives. This problem can be addressed by the application of visible light photonic curing; however, the substrate must be protected and so process parameters must be defined for each material/substrate combination. Here, we report results of a large-scale trial of photonic curing of aqueous flake silver inks on poly(ethylene terephthalate) substrates in an industrial setting. The resistivity of printed patterns after an optimized photocuring regime matched those reported for typical nanoparticle inks; on the order of 100 μΩ cm depending on substrate and geometry. Scanning electron microscopy revealed evidence for structural changes within the printed films consistent with localized melting and necking between adjacent particles, leading to an improved percolation network. Furthermore, in the large-scale industrial trial employing screen-printed silver lines, the manufacturing yield of conductive lines was increased from 44% untreated to 80% after photocuring and reached 100% when photocuring was combined with thermal curing. We believe this to be the first reported observation of an increase in the yield of printed electronic structures following photocuring. We propose a crack-healing mechanism to explain these increases in yield and conductivity. We further report on the effects of the photonic curing on the mechanical bending stability of the printed conductors and discuss their suitability for wearable applications.

A multilayer thin-film screen-printed triboelectric nanogenerator

In this study, we developed a multilayer thin-film triboelectric nanogenerator (MT-TENG) that incorporates a honeycomb-patterned spacer fabricated via screen printing by using ultraviolet curable ink. The printed spacer, a thin polymer layer, and thin metal electrodes enable the formation of a single thin-film structure. When force is applied to the thin-film TENG, the honeycomb-patterned spacer helps the polymer layer deform elastically through the opening of the pattern and contact the electrode. We implemented an MT-TENG by stacking 3 30 mm × 30 mm × 1.4 mm TENG layers electrically connected in parallel. The electrical performances of the manufactured MT-TENG with respect to the open-circuit voltage and short-circuit current were 11.45 V and 4.46 μA, respectively. The instantaneous output power density was 10.56 μW/cm3 (13.30 μW). In addition, an MT-TENG shoe insole was fabricated to harvest energy from human walking. We demonstrated that the fabricated shoe insole could light up 9 commercial green light-emitting diodes during walking to have an open-circuit voltage of about 20 V.