• Ink-jet cartridges

    Ink-jet cartridges

Ink-jet printing

Optimization of the ink, the printing process and the substrate with surface science methods

While inkjet technology is declining in the home and office sectors, industrial applications are recording strong growth. Thanks to the multitude of possible combinations of ink types and substrates, as well as low set-up costs, inkjet printing is a very adaptable process. The quality depends very much on the control of the print heads, on the flight behavior of the droplets and on the droplet distribution on the substrate as well as on its wettability. The method of Drop Watching and the investigation of the static and dynamic surface tension of the ink as well as the surface properties of the substrate are typical applications for our measuring instruments.

Common applications of inkjet printing

  • Packaging printing and individual branding
  • Printing on ceramics, decor and glass
  • Floor coverings
  • Textile printing
  • Printable circuits
  • 3D printing

    Optimization of the printing process and the ink by means of Drop Watching

    Drop Watching is the examination of ink drops immediately after leaving the print head. Ideally, the piezo nozzles of the printhead are controlled directly by the measuring instrument, so that the drop behavior can be observed as a direct effect of the defined waveform. The novel two-color double strobe method allows accurate measurements of volume, velocity, ligament length and the formation of satellite droplets. The results help to match print parameters and ink formulation in a targeted manner to achieve high-quality print results.

    Controlling the ink’s wetting behavior with static and dynamic surface tension

    Drop formation and spreading is largely controlled by the surface tension of the ink, which is commonly lowered with surfactants. Our tensiometers help to adjust the surfactant concentration by measuring the static surface tension. The critical micelle formation concentration (CMC) as an indicator for the surfactant’s efficiency is measured automatically using a wide concentration range.

    To optimize ink in terms of wetting means to regulate the speed with which the surfactant lowers the surface tension. During ink ejection, the surface tension needs to be large enough to ensure meniscus recovery inside the nozzle, and thereby, guarantee a proper drop formation. However, after a very short flight time, the surface tension needs to be low enough to assure proper wetting of the substrate. Our bubble pressure tensiometers monitor the dynamic behavior of the surface tension in a wide range of speed.

    Evaluating the wettability of the print carrier and the effect of surface treatment

    The surface energy of the substrate defines the wettability and partly controls the adhesion between ink and substrates such as paper or plastics. Our Drop Shape Analyzers determine the surface free energy and its division into polar and disperse parts. This energy profile serves to optimize surface preparation steps like plasma or corona treatment.

    As ink-jet printing drops of approximately 100 pL are ejected onto a substrate, our picoliter dosing unit, microscope optics, and high speed camera characterize this wetting process very closely to true environmental conditions.

    Avoiding foam with the help of foam analysis measurements

    Wherever there are surfactants involved in dynamic processes, foam formation can become a challenge to solve. Our Dynamic Foam Analyzer – DFA100 offers highly reproducible methods for measuring foam formation in the short-term range of unstable foams. This makes it a powerful tool for optimizing antifoam agents added to the ink.

    KRÜSS Application Reports

    AR289: How waveform, surface tension, and viscosity affect the jetting behavior in inkjet printing

    The generation of drops at a piezo-based inkjet nozzle is an interaction between the geometry of the print head, the parameters of the liquid, such as surface tension and viscosity, and the wave form with which the piezo element is actuated. Using model liquids, our application report illustrates how these quantities determine the jetting behavior.

    AR269: Investigating the foam-inhibiting effect of antifoaming agents in printing lacquers

    To avoid the numerous quality problems due to foam, antifoaming agents are added to aqueous printing inks and lacquers. The efficiency of two silicone-based antifoaming agents is investigated and compared using foam height measurements with respect to time.

    AR267: Foam behavior and foam stability of aqueous surfactant solutions

    The foaming and stability behavior of three surfactant low-foaming solutions are characterized. Comparative interfacial rheology measurements provide a good correlation between interfacial rheology parameters and the data from the foam measurements.

    AR256: How plastics lose their hydrophobia

    The increase in surface polarity by ozone treatment is proven with the help of contact angle measurement. The results also show the dependency of the degree of surface activation on the duration of the treatment.

    AR221: Wettabilities and Surface Tension of Different Paper Types

    Rapid change of contact angle describes the absorption into porous paper, the capillarity of which is measured in addition with the Washburn method. For coated paper, different hydrophilic behavior is detected via surface energy determination.

    Request more information