Machine Description
Operating Instructions
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ITS6_135_Manual_EN.doc
4.6.8
Corona treatment
Purpose
To improve the wettability of the particular substrate.
Technical realization
Printing substrate is exposed to ionized air generated by an electrical high-
voltage discharge.
Fig. 23. Corona treatment
Pos. Element
Meaning
1
Corona generator Supplies the medium-frequency high-voltage
required for generating the corona.
2
Counter drum
Serves as a counter-pole to the bar electrode
as well as a guide for the substrate.
3
Extraction port
The air at the top of the printer is extracted
through this port and conveyed to the printer
’s
air circulation system.
4
Corona station
The corona station improves the wettability of
the particular printing substrate.
5
Bar electrode
Generates a corona through high-voltage dis-
charge which alters the surface of the sub-
strate being passed through.
The corona treatment is needed especially when printing glossy, plastic
materials in order to improve the adhesion of the applied ink.
Without the corona treatment, the applied drops of ink would behave simi-
larly to water on a layer of grease by maintaining their round form and roll-
ing off to some extent. Also, due to the relatively small areas of contact,
they would coalesce rather poorly on the particular substrate even after cur-
ing, making the transferred images less durable. Furthermore, in some
cases, fine stripes with less intense coloration could appear in the direction
of travel when ink drops applied next to each other fail to coalesce and form
a solid area before curing.
1
4
3
2
5