UV-curable Inkjet Research Articles

Effect of plasma modification on UV-curable ink-jet coating on medium-density fiberboard (MDF)

ABSTRACT The UV-curable inkjet coating system on the surface of wood-based substrates consists of the substrate, primer, printing layer, and topcoat layer. To enhance the compatibility at the interface between the UV-curable primer and the inkjet coating on the substrate surface, this study employed air plasma to modify the medium-density fiberboard substrate's primer surface under varying treatment power and speeds. By analyzing the changes in contact angle, chemical composition, and elemental composition of the substrate primer surface under different plasma treatment conditions, theoretical support was provided for the improvement of the bonding between the UV-curable primer and the printing layer. The results show that with a plasma treatment speed of 0.4 m/min and power of 700 W, the contact angle with water on the surface was 20°, and the whiteness value was 80.5 Wb. The C = C bonds on the primer surface break and combine with oxygen elements to form oxygen-containing functional groups or peroxides, increasing the surface polarity and activity of the primer. When the plasma treatment power was 750 W and the speed was 0.8 m/min, the relative concentration of oxygen elements on the UV-curable primer surface increased to 49%, while the carbon element content decreases by 29%.

Newly Developed UV-curable Inkjet Technology for Forming High-quality Image with High Productivity

Newly Developed UV-curable Inkjet Technology for Forming High-quality Image with High Productivity

Digital 3D Wood Texture: UV-Curable Inkjet Printing on Board Surface

Natural wood textures are appreciated in most forest products industries for their appealing visual characteristics including grain and color, but also their fine surface tactile sensation. The following presents an ultraviolet (UV)-curable inkjet technology printing 3D wood texture on wood-based substrate by image processing and surface treatment. The UV printing was created from scanned digital images of a real wood surface and processed in graphics software. The images were converted to grayscale graphics by selecting color range and setting the parameter of fuzziness. The grayscale images were printed as 3D texture height simulation on the substrates and coated by printing the color images as texture mapping. Based on these wood texture digital images, the marquetry art is also considered in the images processing design to increase the artistry of the printed materials. The medium-density fiberboard (MDF) coated printing marquetry surface replicate realistic natural 3D wood texture surface layers on wood-based panels and imitated the effect of handcrafted wood art works. This study proves that printing 3D texture surface material is creative and valuable with ecologically friendly, low-consumption UV-curable inkjet technology and provides a feasible and scalable approach in flooring/furniture/decorative architectural panels.

Effect of physical parameters and temperature on the piezo-electric jetting behaviour of UV-curable photochromic inks

Although resource-efficient processes like inkjet printing have a large potential to foster the development of smart and functional textiles, one bottleneck still is the development of functional inks. To make inkjet printing and UV curing given production techniques for smart and functional specialty products, e.g. photochromic textiles, deepened knowledge about the development, rheological behavior and jetting behavior of functional ink is needed. This paper focuses on the formulation and performance of UV-responsive and UV-curable inkjet inks, which are based on photochromic dyes and their application to produce UV-responsive textiles. Two commercial photochromic dyes—Reversacol Ruby Red (RR) and Sea Green (SG), which represent dyes of the naphthopyran and spirooxazine class, respectively, have been used to develop the inks. The photochromic inks are characterized according to their physical–chemical and rheological properties in respect to temperature. The influence of temperature on the drop formation of the inks in an industrial print head is analyzed using a high-speed camera, which reveals important information regarding challenges in ink jettability. It was found that the dye structure and type used in the ink can influence the jetting behavior of photochromic UV-curable ink. More pronounced temperature sensitivity of dyes can increase the temperature-related effects of drop formation as was observed for SG ink. The printability of the RR and SG inks is framed and underpinned by theoretical calculations of the Z number. Discrepancies are observed and discussed between existing theory of ink jettability and visual evaluation of the photochromic ink.

Making tablets for delivery of poorly soluble drugs using photoinitiated 3D inkjet printing.

In this study, we investigate the viability of three-dimensional (3D) inkjet printing with UV curing to produce solid dosage forms containing a known poorly soluble drug, carvedilol. The formulation consists of 10 wt% carvedilol, Irgacure 2959, and a photocurable N-vinyl-2-pyrrolidone (NVP) and poly(ethylene glycol) diacrylate matrix, with the intention of forming an amorphous solid solution for release of carvedilol. Characterization of the printed tablets showed that the drug is an amorphous state and indicated hydrogen bonding interactions between the drug and cross-linked matrix. Several simple geometries (ring, mesh, cylinder, thin film) were printed, and the surface area to volume ratio of the prints was estimated. Over 80% carvedilol release was observed for all printed tablet geometries within ten hours. The release behaviour of carvedilol was fastest for the thin films, followed by the ring and mesh geometries, and slowest in the cylindrical forms. More rapid release was correlated to an increased surface area to volume ratio. This is the first study to implement 3D UV inkjet to make solid dispersion tablets suitable for poorly soluble drugs. Results also demonstrate that high drug-loaded tablets with a variety of release profiles can successfully be accessed with the same UV-curable inkjet formulation by varying the tablet geometry.

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.

Newly developed UV-curable inkjet technology for forming high quality image with high productivity

We have developed a new and unique UV-curable inkjet technology for a sheet-fed inkjet digital press AccurioJet KM-1, which achieves offset like high quality image with high productivity; 3,000 sheets per hour. A number of AccurioJet KM-1 have already run in the production lines of customers, and have gained reputation as "Real Digitalization Pioneer" for commercial printing industry. The single-pass inkjet printing technology, one of the key technology for the high productivity, is still a big challenge for image processing. To avoid the dots coalescing, we developed a new ink formulation and curing process which can control the ink viscosity precisely in the print head and on the recording media. We also improved the technology which can control the gloss level of the image. Combining them, we succeeded to develop a printing system which achieves offset like high quality image with high productivity.

Newly developed UV-curable inkjet technology for forming high quality image with high productivity

Newly developed UV-curable inkjet technology for forming high quality image with high productivity

The chemo-rheological behavior of an acrylic based UV-curable inkjet ink: Effect of surface chemistry for hyperbranched polymers

Abstract A polyester-amid based hyperbranched polymer (HBP) with hydroxyl terminal groups is modified by the aid of saturated fatty acid groups with 7 carbon lengths. FTIR results reveal that about 85% of hydroxyl terminal groups were replaced by fatty acid chains. Having prepared and characterized the inferred modified HBP, the effect of both neat and modified forms of HBP was tested on the curing behavior of an acrylic based UV-curable inkjet ink by time-resolving photo rheo-mechanical spectroscopy (TRP-RMS). The chemo-rheological results of TRP-RMS show that the hyperbranched polymers, in both neat and modified forms affected the rheological behavior of the ink during the curing process. In this research, slope of estimated line on the chemo-rheological curves was used to measure the rate of complex viscosity growth of ink formulation during the curing process. Accordingly, slope in the blend without HBPs was 180.56 Pa and it increased to about 300 Pa on addition of HBPs even at a loading of as much as 2 wt.%. Results demonstrate that hyperbranched polymers have altering influence at the various different stages of the curing process.

Towards UV-curable inkjet printing of biodegradable poly (lactic acid) fabrics

There has been growing interest in using poly (lactic acid) (PLA) fibres because of its natural-based origin and good biodegradability; however, its adoption within the textile industry has been limited to lower temperature wet and dry processing, because of its relatively lower glass transition temperature (T g) and melting point (T m). Here we report for the first time inkjet printing of heat-sensitive PLA fabrics using ambient temperature UV-curable inks as a way of overcoming the potential degradation at higher temperature. The UV cured inkjet printed PLA fabrics exhibited good performance characteristics such as acceptable colour fastness, relatively high colour strength, K/S, and comparable colour difference, ΔE, after washing to the thermally cured ink system, without affecting the physical and mechanical properties of the fabrics. In contrast thermally cured inkjet printed PLA fabrics exhibited significantly reduced bursting strength and stiffer handle attributed to the thermal degradation and lower fibre flexibility imparted at the higher temperature. Investigation of the radiation-cured printing approach indicates UV-curable inkjet printing may be considered as an alternative to conventional thermally cured pigment printing of heat-sensitive biodegradable PLA-based fabrics.

Newly developed UV-curable inkjet technology for Digital Inkjet Press “KM-1”

We have developed a new and unique UV-curable inkjet technology for a sheet-fed off-set like inkjet printer "KM-1", which will bring a new wave of digitalization into the commercial printing world. There were many technical challenges to realize both high-speed and high-quality recording process in a system. We studied the imaging process thoroughly and reached a new and unique UV-curable ink formulation and a process that can cure images at extremely high speed with extremely high definition. To support the ink and the process, we also developed a variety of technologies such as a new durable print head with high nozzle density, an image correction system, and so on. Combined these new technologies, as a synergy of inks, print heads, and system, we have succeeded to develop a new inkjet printing system for digital press market.

UV-curable encapsulation of surface—Modified organic pigments for inkjet printing of textiles

Aqueous dispersions of nano-scale organic pigments were prepared through ball milling and ultra-sonication in presence of dispersing agents. The well dispersed pigment was encapsulated into UV-curable resin via miniemulsion technique. Effects of molecular structure of organic pigments, type of dispersing agent and time of ball milling were investigated. Results showed that C.I. Pigment Green 7 had better dispersion stability with time compared with other pigments. Ultracentrifuge sedimentation test, shelf life stability, thermal gravimetric analysis (TGA) and transmission electron microscope (TEM) provided supporting evidences for the encapsulation of C.I. Pigment Green 7 into polyester tetra acrylate/1,6-hexandiol dimethacrylate. Zeta potential results proved that UV-curable encapsulation of C.I. Pigment Green 7 intensifies the charge on the surface of the pigment and significantly increases the dispersion stability. This method of modifying organic pigments to be used as pigmented UV-curable inkjet inks was found to be durable and effective in preliminary application in inkjet printing of textiles.

Development of Printing Method to Produce High-glossy Images with UV Inkjet Printer

While UV-curable inkjet printers have come into wide use, these printing systems have a few problems to be solved. We took notice that the printed images showed relatively low gloss. The decrease in gloss is known to be caused by the fact that UV-curable ink changes into solid before leveling off under irradiation of UV light. We have been trying to develop the new application of UV-curable inkjet printing to obtain high glossy images on the surface of various articles. We had already presented a prototype as one of such trials at ICJ2012, the annual conference of the Imaging Society of Japan in 2012. The process was called DVT which was the decompression transfer printing process with a UV-curable inkjet printer and a vacuum chamber. The DVT had some problems such as low image quality and troublesome process with manual operation. The first improved process which was called DVT-I was proposed at ICJ2013 held in Tokyo last June. However there still remained a few problems, so that we have continued our study and then developed an automated machine in this study. High image gloss has been obtained by excluding air bubbles during the decompression process. Thus we have been able to create products with high quality and glossy images on the surface of various articles.

Development of Digital Quasi-embossing Technology with an Inkjet Printer-2

Conventional embossing printing technology which can be used to produce metallic glossy images on stereo-shaped objects needs a pressing plate with the image patterns specially arranged. Accordingly, the embossing system is relatively expensive and lacks the adaptability for high-mix low-volume production. Considering these facts, we developed the Digital Quasiembossing Technology (DQT) which consisted of the technology combined with UV-curable inkjet printing and hot foil-stamping. We reported the DQT for the first time at NIP 28 in Quebec City last year. This paper is a continuation of the last report and describes the following facts. (a) We have improved the adhesion of UV-curable ink to a metallic foil, and consequently we can make not only relatively small-sized products but also large-sized ones with pictures and letters printed thereon. (b) The improved DQT system can produce higher gloss than the last system reported at NIP 28.

Key Innovations that allow Low Migration Digital Printing with UV-curable Inks

The advent of digital printing techniques about 30 years ago, announced a new era at first in small scale office and home printing, further has emerged in industrial scale printing in a large variety of wide and super wide format applications and is now being rolled out in even more exciting applications ranging from high speed document printing over (food) packaging to product decoration and shows even strong growth in ceramic tile printing.This paper focuses on the use of UV-curable inkjet inks for food packaging applications. Agfa has been playing a leading role in Low Migration digital printing with UV-curable inks and is continuously performing necessary research to keep this leading role. As inkjet printing technology evolves, also the inks have to evolve accordingly. Unfortunately for Low Migration printing, one of the trends goes to lower viscosity inks to cope with the newest generations of high speed, high resolution printheads. Even lower viscous monomers have to be used, increasing the migration risk. The current paper covers specific innovations in terms of chemistry to be able to combine low viscosity and low migration: the main focus lies on the use of a primer to capture any migrating monomer molecules.

Study on the Printability of UV-Curable Inkjet Ink on Different Printed Materials

The printed materials used for UV-curable inkjet ink have diversity, in order to research the differences of the printability of UV-curable inkjet ink on different printed materials and improve the printing quality of UV-curable inkjet ink printing on different materials, this research select coated paper, glass card adhesive paper, PVC plastic film as printed materials. After printing the same UV-curable inkjet ink,the printing quality indicators of printing proofs including the density of the line, blurriness, raggedness, line width and contrast of printing product lines were tested,and then test the contact angle of UV-curable inkjet ink on three printed materials, combined with wetting situation，analysis the printing quality of UV ink-jet ink on different substrate, prepare UV ink-jet ink with different printability, printing and testing the printing quality, assessing the quality with comprehensive evaluation method. The result shows that it's existed large differences among the printing quality of the same UV-curable inkjet inks printing on different materials. We match the printed materials with the corresponding printability of UV-curable inkjet inks in the practical production, in order to get the best printing results.

Development of Digital Quasi-embossing Technology with an Inkjet Printer

Emboss technology utilizing hot-stamping method can produce stereo-printed images with metallic gloss. Conventional emboss method needs an engraved plate and consequently becomes costly especially for a small quantity production. We have developed a new technology with combining UV-curable inkjet printing and hot-stamping processes, where any engraved plates are not used. The new technology called “Quasi-embossing Technology” consists of the following three steps: (1) On the basis of three-dimensional image data, stereo-printed images are formed with a UV-curable inkjet printer, where the print-head accompanying a UV irradiation setup scans several times. (2) A metallic foil which has a hot-stamping adhesive layer is placed on the stereo-printed image with supplying heat and pressure from the back of this foil. (3) After having been cooled, the surplus foil around the stereo-printed images made from UV-curable inkjet ink is removed. Finally three-dimensional products with metallic gross are obtained. This technology is applied to produce various products including conventional emboss printing ones.

New Digital Pad Printing Technology Using Inkjet Printers

When printing with conventional UV-curable inkjet printers, it is almost impossible to obtain high-resolution images on the uneven printing media such as molded plastic products with undulations of more 3mm. This study is related to the new digital pad printing technology; which produces high-quality images on such uneven surfaces. The process to produce images is as follows: (1) Inkjet printing is carried out on a heated silicon rubber film with UV curable ink diluted with an organic solvent. This solvent evaporates immediately after the ink droplet reaches the film surface, making the ink viscosity higher: Thus the spread of the printed ink dot stops. This results in sharp printed images. (2) A soft pad is applied to the backside of a silicon rubber film, which can be pressed against an object, thereby transferring the ink image onto the object's surface. (3) Finally the UV irradiation makes the ink hard. Through this process, we can decorate various objects with high-quality images.

The Study of the Influence of Photoinitiators on Curing Rate in UV System under Different Oxygen Atmosphere

The UV system contains prepolymer, monomer and photoinitiator has been broadly used in printing area. UV-curable inkjet ink with its environmental protection, energy-saving, good printing quality and high efficiency has become the most concerned topic and has a good development prospects. The use of UV ink-jet printing ink in ink-jet digital printing is the main development trend of digital printing currently and a period of time in future. Curing rate is one of the most important performance parameters of the UV system which is greatly affected by prepolymer, monomer and photo-initiator, besides that, the oxygen atmosphere is another principal element. In order to investigate the influence of different oxygen atmosphere on the curing reaction, we designed and made a UV curing device with varied degree of oxygen atmosphere to study the effect of photo-initiator species and content on the systems curing rate under different oxygen atmosphere condition.

Collins Ink acquires Hexion’s UV curable inkjet, optical disc coating business

Collins Ink acquires Hexion’s UV curable inkjet, optical disc coating business