ESA for metallized films or boards
In food packaging, metallized films or boards are used to provide a barrier to light, oxygen, water and odours. In gravure printing, Electrostatic Printing Assist Systems (ESA) are used to eliminate so-called “missing dots”, where the ink has not been transferred from the cell of the gravure cylinder to the substrate.
In general, ESA systems represent the current state-of-the-art in gravure for illustration or packaging print, and by ensuring full ink transfer from the cell to the substrate are a must for all quality printing.
All common ESA systems work on the principle of applying a high DC voltage to a specially made ESA impression roller.
A direct current will flow, depending on the charging system and the conductivity of the ESA impression roller, through the non-conducting printing substrate to the electrically earthed gravure cylinder.
Ink is a mixture of various materials such as pigments, solvent and binding agent, and the dipoles of its components are polarized by the direct electric field, resulting in an increase in ink volume in the cell, which improves ink transfer to the substrate.
The underlying physics means that all common ESA systems, whether indirect or direct charging, do not work on metallized substrates.
Spengler goes Eklektika
To meet the demands of premium printers from around the world for an ESA system suitable for electrically conducting substrates, Spengler’s team of experts invented a system that can handle all kinds of metallic substrates.
For operational reasons, it may be necessary to modify the substrates and some parts of the press.
Spengler of Switzerland’s Eklektika charging system is suitable for the following substrates:
- metallized PET or PP film
- metallized PET or PP film on paper or board
- laminated aluminium foils on paper or board
- aluminium foils with lacquer coating
The Eklektika charging system can be installed on all common gravure presses and does not require specially made ESA impression rollers, making the system more cost effective than classic ESA systems.
It is also easy to integrate it into our classic ESA applications if there is a need to print on non-conducting substrates like paper, board or films.
Spengler offers a wide range of charging systems to suit customer requirements, press conditions and the ESA impression rollers.mAll of our systems are state-of-the-art and fully comply with all the legal requirements of the European ATEX Directive 2014/34/EU for explosive atmospheres.