Standard Inks Research Articles

Self‐Healing, Recyclable, Biodegradable, Electrically Conductive Vitrimer Coating for Soft Robotics

AbstractSensors and transducers enable the robots’ movements and interactions with humans and the environment. Particularly, tactile and motion sensors, even those inspired by the human skin, often miss many of its essential features. Indeed, the materials that constitute such sensors are often rigid and lack self‐healing and biodegradability. Furthermore, the large‐scale diffusion of these technologies propelled by robots spread in many aspects of the lives, from industrial to household settings, contributes heavily to the electronic and robotic waste problem. Recycling strategies for materials for robotics sensors are thus pivotal for future development. This work proposes self‐healable, recyclable, and biodegradable electrically conductive coatings. These coatings are based on conductive inks that combine graphene nanoplatelets and carbon nanofibers with a soft biodegradable vitrimer binder and are realized by spray coating. The use of the vitrimer ensures satisfying adhesion to diverse substrates, flexibility, conformability, self‐healing, and recyclability of the conductive coating. This material is a sustainable alternative to standard conductive inks for flexible electronics and soft robotics. Indeed, tests for the live monitoring of SoftHand3, the grasping system of many worldwide diffused robots, have yielded promising results. The use of biodegradable ingredients and the possibility of recycling makes it an appealing material to face the sustainability issue of today's electronics and robotics.

Use of Functional Ink in a Smart Tag for Fast-Moving Consumer Goods Industry

In the fast-moving consumer goods (FMCG) industry, current labelling solutions have challenges to meet the track & trace requirements. Currently, FMCG items use mainly paper-based self-adhesive labels with traditional barcodes. These labels are low priced and technically easy to produce and deploy. The shift towards advanced solutions, like radio frequency identification (RFID) or near field communication (NFC) tags, still does not offer a good enough cost/benefit ratio. These advanced solutions have a high unit price or require costly changes in production lines. Still, the industry recognizes the possibilities of smart tags. Recent research has shown that functional inks can operate as cheap sensors. However, more research is needed to take functional inks into the operational FMCG environment. This paper presents one technical solution for an FMCG smart tag. The proposed smart tag builds on traditional QR-Code and Datamatrix markers, printed with standard inks. However, it also has functional ink embedded inside the marker as a sensor. This research experiments how embedding impacts the overall performance of the smart tag decoding. And if the CIEDE2000 color difference algorithm can calculate the state of the sensor. Three different parameter combinations, CIEDE2000(1, 1, 1), CIEDE2000(2, 1, 1), CIEDE2000(2.76, 1.58, 1), and their accuracy are compared. Experiments show that the proposed approach does not negatively affect the decoding performance. And that a color comparison can detect sensor states, especially when the functional ink has high enough color intensity. Between different parameters, CIEDE2000(2.76, 1.58, 1) performed best, especially in the low-intensity test. However, some future research needs to address absolute color value detection and the accuracy of color recognition; especially when if the color has low intensity.

The Amber Project: A Survey of Methods and Inks for the Reproduction of the Color of Translucent Objects

Unlike regular pigments based on selective light absorption, the so-called “effect pigments″ are based on the phenomena of structural color, or selective reflectance. Structural color has appealing aesthetic qualities, such as angle-dependent hue, and is able to produce lightfast colors. When used as a pigment, however, the gamut of the print is more limited, the color is difficult to measure, and therefore color management and preprint process become challenging. The aim of this paper is to compare the behavior of effect pigments in the processes of lithographic and screen printing with standard pigments used in so-called process inks, and to analyze their optical properties when used on their own or in combination with absorption pigments. An image of amber beads was printed as screen prints and lithographs. Three sets of inks were used: Set one: Standard process inks in the colors cyan, magenta, yellow and black (CMYK); set two: RGB inks formulated with Merck Spectraval™ pearlescent pigments which allow additive red, green, blue printing on a black substrate; and set three: golden inks formulated with pigments from the Merck Iriodin™ and Pyrisma™ effect pigment range. The image was printed on white and black paper. The optical appearance was assessed visually, and spectra and color coordinates were measured.

Water-based flexographic ink using chalcones exhibiting aggregation-induced enhanced emission for anti-counterfeit applications

In pursuit of fluorescent pigments, a pyrene-based chalcone 1-(4-chlorophenyl)-3-(3a1,6,8a,10a-tetrahydropyrene-1-yl)prop-2-en-1-one (CPP), which exhibited aggregation-induced enhanced emission was synthesized. Water-based eco-friendly flexographic inks were formulated using CPP (in batch ink) and Luminous yellow RG-3 (in standard ink) as pigments. The batch and standard inks were coated on security paper and printed on security and packaging papers as well as boards. The printed substrates displayed yellow fluorescence upon excitation under UV light. The gloss, light-fastness, abrasion resistance and colorimetric values of the batch ink were superior to that of standard ink. The study revealed the potential of CPP as a fluorescent pigment for security printing applications, optical-electronic devices such as transistors, anti-counterfeiting labels, etc.

Reversible Conductive Inkjet Printing of Healable and Recyclable Electrodes on Cardboard and Paper.

Conductive inkjet printing with metal nanoparticles is irreversible because the particles are sintered into a continuous metal film. The resulting structures are difficult to remove or repair and prone to cracking. Here, a hybrid ink is used to obviate the sintering step and print interconnected particle networks that become highly conductive immediately after drying. It is shown that reversible conductive printing is possible on low-cost cardboard samples after applying standard paper industry coats that are adapted in terms of surface energy and porosity. The conductivity of the printed films approaches that of sintered standard inks on the same substrate, but the mobility of the hybrid particle film makes them less sensitive to cracks during bending and folding of the substrate. Damages that occur can be partially repaired by wetting the film such that particle mobility is increased and particles move to bridge insulating gaps in the film. It is demonstrated that the conductive material can be recovered from the cardboard at the end of its life time and be redispersed to recycle the particles and reuse them in conductive inks.

Bio-based polyester itaconates as binder resins for UV-curing offset printing inks

UV-curing inks have several economic and environmental advantages compared with standard printing inks, such as high printing velocities, low VOC emissions and good adhesion to nonabsorbing substrates. However, there are also some drawbacks, such as residual monomers, pungent odor and allergic potential of monomers and prepolymers derived from acrylic acid. In addition, only few examples of UV-curing inks derived from renewable resources are known. Herein, acrylate-free UV-curing polyester itaconates with a renewable content up to 100% and their application as binder resins in UV-curing offset ink formulations are presented. In order to obtain a high renewable content in the polyester resins, Zn(OAc)2 had to be used as polycondensation catalyst, as standard Bronsted acid catalyst led to undesired side reactions. The resins obtained with this synthetic protocol were tested on their reactivity, which was slightly lower than a commercial polyester acrylate. Printing inks formulated from these polyester itaconates showed interesting properties despite the fact that no acrylic acid was incorporated in the resins.

Nonhazardous Solvent Systems for Processing Perovskite Photovoltaics

Replacing toxic solvents with nonhazardous solvents is one of the key challenges for industrial scale commercialization of thin film perovskite photovoltaics. Here, nonhazardous solvent/alcohol/acid systems are presented for the single‐step deposition of pinhole‐free perovskite layers with combined lead halide precursors of Pb(CH3CO2)2·3H2O, PbCl2, and CH3NH3I. Comparable performance to standard hazardous inks is achieved: devices with 15.1% power conversion efficiency are demonstrated and maintain 13.5% tracked for 5 min at maximum power point. Blade coated 4 cm2 solar modules fabricated with highest performing device ink attain 11.9% in power conversion efficiency.

Ink-Jet Cartridge Lifetime

Extensive examination of thermal ink-jet cartridges has revealed that their maximum lifetime is limited by two major mechanisms: The first is the deterioration of the heaters caused by the ink-jet propelling bubble combined with the high temperature of operation of the heaters. The second is deterioration caused by direct current leakage from the heater through the ink chamber creating unwanted electrolytic byproducts. To eliminate both of these effects, it is proposed to eliminate the electrical heaters used to generate the propelling bubble and replacing them by electrodes passing a high-frequency current through the printing ink to form a propelling bubble. To evaluate this system, it is necessary to experimentally determine the electrical characteristics of the ink to determine the efficiency of heating by the applied current, in the range from 100 KHz to 200 MHz. It was found that standard ink-jet inks, now in use, can be efficiently coupled to the drive transistors within this range without altering ink composition

Permanent magnetic thick films from remanence optimized NdFeB-inks

NdFeB films with thickness between 10 and 50 μm are prepared by screen printing of standard inks containing 70–80 wt % of NdFeB powder (MQP-B). The coarse MQ-powder is fine-milled to give a mean particle size of about 10 μm in order to obtain well-printable inks and homogeneous films. Typically, remanent inductions of 200–320 mT are obtained. The maximum loading of magnetic powder in the ink is increased to 85–90 wt % by optimizing the powder-particle packing. Mixtures of MQ-powders of different grain size were prepared in order to maximize the powder's tap density and reduce the interparticle volume. Inks prepared from such powder mixtures display an increased remanence of up to 500 mT. Screen-printed NdFeB thick films are important components for miniature actuators or micro-electromechanical systems. In miniature systems the magnetic component has to provide a strong field without having a large size. Therefore, the reported enhancement of the remanence of NdFeB inks for screen printing of magnetic thick films represents dramatic progress compared to standard NdFeB inks.

Innovative Ink Jet Inks for Textile Printing

The development of inks is a very complex field, in which the currently available systems have been tailored to individual ink jet print head technologies. We focus on ink jet solutions for the textile industry, where for digital printing a bright future is predicted. Technological requirements are much more challenging compared to the standard inks used in the SOHO-market. In order to be competitive to conventional textile printing, very reliable prints are necessary, which can currently only be achieved by the piezo technology. In addition, prints have to exhibit superior properties concerning chemical and mechanical resistance. Therefore, adhesion promoters and binding functions have to be added.This paper outlines our recent developments in the area of universal pigment inks suitable for all kind of textile substrates such as cotton and polyester. We have introduced an innovative ink set into the market, which contains a new multifunctional agent (MFA). Our MFA exhibits unique properties concerning dispersing organic pigments, stability of inks, adhesion on different textiles and high mechanical resistance. All these functions are combined in one polymer by tailoring the functional units to the pigment and the textiles.The prints on textiles exhibit high light fastness, outstanding rub and wash fastness levels equal to conventional textile printing combined with a extremely soft handle. We are convinced, that this new ink technology will open new applications for digital printing in the classical and new textile world.

Reproducing color images with embedded metallic patterns

By combining a metallic ink and standard inks, one may create printed images having a dynamic appearance: an image viewed under specular reflection may be considerably different from the same image viewed under non-specular reflection. Patterns which are either dark or hidden become highlighted under specular reflection, yielding interesting visual effects. To create such images, one needs to be able to reproduce at non-specular reflection angles the same colors, by standard inks alone or in combination with a metallic ink. Accurate color prediction models need to be established which model the underlying physical phenomena in a consistent manner. To meet this challenge, we propose two models, one for predicting the reflection spectra of standard inks on coated paper and one for predicting the reflection spectra of a combination of standard inks and a metallic ink. They are enhancements of the classical Clapper-Yule model which models optical dot gain of halftone prints by taking into account lateral scattering within the paper bulk and multiple internal reflections. The models we propose also take into account physical dot gain and ink spreading for standard inks as well as the low reflectance of metallic inks at non-specular reflection angles and the poor adherence of standard inks printed on top of a metallic ink (trapping effect). These models open the way towards color separation of images to be reproduced by combining a metallic ink and standard inks. Several designs printed on an offset press demonstrate their applicability and their benefits for high-end design and security applications.

New densification process of thick films

Standard inks for low-cost screen-printed components generally contain a glass binder for adhesion and filling. However, for applications where the original properties of the active material must not be changed, a glass-free ink is highly desirable. To ensure a good densification of screen-printed films without inorganic binder, it is proposed that the application of a mechanical pressure be added to the standard process. This new process has been used to fabricate low-voltage single-in-line varistors, capacitors, and pyroelectric components with sandwich electrodes. Such a configuration is difficult to obtain when, as in the standard screen-printing procedure, no pressure is applied to the films. Conductors, resistors, and semiconductor chemical sensors prepared with this technology have also been investigated.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The Paper Mate® Ink on the Howard Hughes “Mormon Will”

Abstract Ink analysis was performed on the Howard Hughes “Mormon Will” case to determine if the inks matched standard inks available at the alleged date of the will, that is, 16 March 1968. The ink on the will matched a standard ink made by Paper Mate between 1966 and 1972. Consequently, no conclusion can be made regarding authenticity. However, both the proponents and contestants of the will used these inclusive results along with other facts to support their own views of authenticity or fraud.