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NEWS
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ATMOSPHERIC PLASMA SYSTEM (APT system)
FOR AN IMPORTANT ITALIAN CONVERTER
It is under operation by an important italian company specialized in the converting industry a new MERO atmospheric plasma treatment system.
They have been installed n.2 treatment groups on a rotogravure machine with lamination process in line. The first group is positioned after the primary unwinder and treats the material before the printing stage, the second one is placed after the secondary unwinder and treats the material before the laminating stage.
The two systems must guarantee a perfect adhesion of the ink and of the laminating glue at very high speeds (500 m/min) even on not pretreated substrates. For this purpose we have chosen a power of 18 kW for the generators. The materials to be treated can be both transparent and metallized, that is why the discharge station is universal style with ceramic bars electrodes and discharge roller covered with special high thickness ceramic.
The fundamental novelty is in the discharge station, which allows to have the discharge not in air (corona system) but in a preselected gas mixture (Atmospheric Plasma system). It has been seen infact that for certain processes the presence of Oxygen in consistent percentage under the electrodes determines a decrease of the adhesion properties of the treated substrates. By blowing a special mixture of gas in a controlled way under the electrodes, the Oxygen can be almost totally removed with evident advantages.
The gas used can be many different types like Nitrogen, Argon, Helium or also reactive gas that can create a sort of grafting phenomenon on the surface of the material.
The interesting thing is that the system can be used as an atmospheric plasma system or when not required can work as a corona system simply interrumpting the flow of gas in the chamber.
ALWAYS AHEAD IN THE TREATMENT OF CPP FILM!
In the last part of 2008 n.2 new CPP lines with very high productivity have been installed in Italy. Both lines have a width of more than 3 meters with a speed that can reach 350 m/min. The treatment of CPP at these high speeds can be a problem especially if high levels of surface tensions are required.
Only a company with an historical experience on the treament of CPP could be chosen for this difficult application, and for this reason both customers made the choice of MERO.
In both lines it has been installed a double side corona system for high speeds.
On both systems they have been chosen n.2 power supplies with 35 kW max exit power. Both sides can be treated in a differentiated way.
The secret of success on such an application stays in two main factors, reliability of the power supplies and uniformity of the air gap even in conditions of full power discharged. The reliability of the MERO generators comes from the great experience on the BOPP film (more than 400 running installations all over the world with generators up to 70 kW of exit power).
For what concerns the second point, what makes the air gap stable is the special design of the electrodes that allow a perfect expansion of the discharge points even at high power. This means that the air gap setted before starting remains perfectly uniform under operation conditions with a consequent guarantee of uniform surface tension along the width of the film.
The station is equipped with pressure rollers (one for each side) to avoid back side treatement and a spreader roller in front of the first corona roller to open up the film and eliminates any wrinkle that could enter under the electrodes.
