Soile Passoja, Jorma Koskinen, Robert Roozeman

Abstract
The influence of electric field on gravure ink lifting from engraved structures was studied. Ink transfer without electric field occurs only if the physical contact between ink and paper in the nip is achieved. The use of electric field in ink transfer promotes the ink lifting and enables the contact between ink and paper before the actual nip contact. In a nip a non-uniform electric field lifts the ink near the engraved edges over the cylinder surface. This phenomenon is explained by dielectrophoresis and supported by simulation. The electric field lifts the liquid on a microsecond timescale and it defines the ink transfer in gravure as the nip contact in the real press occurs on a millisecond timescale.

Keywords: Gravure printing, Electric field assistance, Ink transfer
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Gert Schlegel, Arved Hübler, Robert Thieme, Alexander Böddicker, Thomas Hädrich, Günter Wozniak

Abstract
This paper has two objectives: First, it aims at defining theoretically and determining by means of experiments ink film formation of sprayed offset printing ink. This refers to the analytic description of the surface covering process in the inking system of an offset printing press. Influencing factors are the temperature-dependent, rheological properties of the printing ink and the resulting drop size spectrum of an offset printing ink sprayed with a two-component jet (external mixture). The main problem is to transfer standard, highly viscous, sticky offset inks into a sufficiently fine spray that guarantees a fine, homogeneous ink film on an ink carrying roller in the inking system of an offset printing press.

The second aim is to design a prototype of a functioning spray inking system and to determine optimum working parameters for the employment of this new inking system in an offset printing press. The analysis is focused on standard offset printing ink (heatset ink, black). Practical tests are done on a rotary offset press.

Keywords: Offset printing, Inking unit, Atomization, Spray, Nozzle
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Tatiana Sretentseva, Julia Timchenko

Abstract
This paper is devoted to the investigation of the influence of the composition, functionality, nature and rheological characteristics of the model vehicles on rheological properties (anomaly of viscosity, the yield stress Pk) of model UV curing inks for screen printing. Also we have studied the dependence of the rheological characteristics of model inks (viscosity, yield stress, structuring degree, structure strength, rate of destruction and reconstruction of the structure, rate of thixotropy) on concentration and functional features of a number of pigments added to the ink compositions.

Keywords: rheology, yield stress, anomaly of viscosity, thixotropy, screen printing inks.
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