FAQ
CORONA TREATER
Now under the influence of the electric field, ionized air molecules are made to move about. As the electric field increases, so does the speed and hence the kinetic energy of ionized air molecules. The random collision of these ions with other charged ions result in increased number of ions. Thus when sufficient electric field is developed, then the air gap can be said to have broken down into an ionized current carrying conductor. During this process the atmospheric oxygen is broken down into nascent oxygen and Ozone. The ozone is extracted out of the system where as the active nascent oxygen immediately oxidizes the film.
The power faction (w/m2/min) is calculated basis the graph below :
Taking into consideration the operating conditions, the Corona Treater should be designed such that the systems are of robust design and operator-friendly.
For better post-treatment results of the film, surface energy should be adequately optimized. In case of over treatment, which is quite possible in case of PE substrates during the extrusion process, blocking of the film may take place which would then hamper the subsequent unwinding and tension controlling process. Also over treatment reduces the heat seal ability of the film in case the treated side need to be sealed with some other substrate.
In case of under treatment, the film may have low wet ability and correspondingly low dyne levels which would then cause ink peeling in case of printing or delamination in case of lamination process.
Although dyne testing pens are easily available in the market, using a freshly-made uncontaminated dyne solution is the better way of testing dyne level of substrates.
Printing is essentially an adhesion phenomenon between the substrates and the ink. It is not easy to determine the surface tension of the inks. The basic thumb rule should be that the surface tension of the Substrate which is to be printed should be 7 dynes/cm higher than that of the ink which is to be applied.
During high speed treatment processes, if the substrate wrap angle is less than 180 degrees then because of the venturi effect, a differential pressure sets in which tries to lift us the substrate from the roller. As a result of this, air beneath the substrate also gets ionized and the opposite side gets treated which sometimes is not desirable in case of heal-seal application.
Also back side treatment can be caused, if the surface of the roller is kept unclean or if there are dents or pits formed onto the surface of the roller due to corrosion. Backside treatment can be avoided by using a nip roller at the entry of the film onto the Treater roller which ensures that a good wrap angle is established between the substrate and the treater roller. Also the surface of the treater roller needs to be kept clean at all times to prevent the unwanted backside treatment.
Improper web tension can lead to wrinkles in the substrate which in turn would lead to the undesired back side treatment. Also if proper web tension is not maintained, the wrap angle of the Substrate with roller gets hampered.
General preventive maintenance schedule needs to be followed as instructed in the operation manual. Also in case of universal treater where in ceramic electrodes are used, proper cleaning and maintenance of these electrodes is essential. The electrodes and electrode holding blocks need to be cleaned with Acetone/Iso Propyl Alcohol solutions.
Improper maintenance of the ceramic electrode can lead to premature failure or cracks. Also ensure that the Ozone extraction system is properly maintained and a good negative static pressure is maintained in the ducting chamber. Proper cleaning of Treater roller is essential to prevent corrosion or contamination with the external dust or foreign particles.
PLASMA TREATMENT
Plasma is generally described as an ionized gas or as an electrically neutral medium of positive and negative particles. "Ionised" refers to the presence of free electrons which are not bound to an atom or molecule. Plasma or "Radiant Matter" as it was known, was first identified by Sir William Crook in 1879. Radiant Matter was later called "Plasma" by Irving Langmuir in 1928. Plasma is the most common type of matter in the known universe whether measured by mass or volume.
Every star is a giant ball of plasma, even the space between all of the stars is composed of plasma. Plasma is considered to be the 4th state of matter after solid, liquid & gas. In general terms, when you add enough energy to atoms or molecules, what happens very quickly is that the electrons around the nucleus start to "boil off", the temperature becomes too high for them to stay in orbit around the nucleus. Plasma discharge can be used for surface modification.
Approximately 1 kw power is required.
Plasma can be created in a Vacuum chamber or be ejected from an Atmospheric Plasma nozzle so treating a wide variety of shapes is possible.
No, the mass of your parts remains unchanged.
Yes, any part of the surface can be masked to shield it from the effects of the plasma.
Typical treatment speeds of up to 30m/min are common, for higher speeds additional nozzles can be added.
Plasmas are a mixture of both charged particles and neutrals (atoms, radicals & molecules) and can react with a wide range of materials. Plasmas are widely used for the cleaning of surfaces, removing organic contamination from metal, rubber and plastics. Plasma Cleaning is a "Dry" cleaning process and can replace environmentally damaging chemicals e.g. chlorinated hydrocarbons (trichloroethylene) and is ideal for the surface cleaning of metal pressings/fabrications before bonding, sealing, painting and the removal of organic residues or oxidation from surfaces prior to bonding, soldering or wire bonding on a variety of metals e.g. gold, silver, titanium, copper.
Typically the surface of the part being treated will be raised by no more than 10 ºC. Vacuum plasma operates at around 20 - 50 ºC. and Atmospheric Plasma at around 230ºC, this is much cooler than that of a normal gas flame.
Unlike corona treatment Atmospheric Plasma does not produce any ozone.
No, Atmospheric plasma simply requires an oil-free and dry compressed air supply and a standard 230V 13 Amp electrical supply.
Typically between 8 - 20 mm, depending on the materials to be treated and the required treatment levels.
Plasma Cleaning is a "Dry" cleaning process and can replace environmentally damaging chemicals such as chlorinated hydrocarbons (trichloroethylene). Plasma is ideal for the surface cleaning of metal pressings/fabrications before bonding, sealing, painting and the removal of organic residues from surfaces prior to bonding, sealing, painting, soldering or wire bonding on a variety of metals e.g. gold, silver, titanium, copper or the removal of oxidation from plastics, rubbers and elastomers.
Cold Plasma is a low energy, low temperature Plasma that is created in Atmospheric conditions (not in a Vacuum chamber). It can be used to clean and/or activate surfaces and is ideal for treating materials that would otherwise be damaged by the higher temperature conventional atmospheric plasma system.
There are many advantages to using “Eltech’s” plasma surface technology. The main advantage is the enormously high efficacy when compared to other methods for the activation of surfaces. The Eltech’s plasma surface treatment technology simply results in better and more durable surface activation. Eltech’s plasma systems are also very easy to integrate into existing production lines, they are environmentally friendly, space-saving and have low operating costs.
Public current (230V/400V) as well as a compressed-air supply are sufficient.
The result of the surface treatment depends on the speed of the passing material, on the effective distance of the nozzle end, and on the width of the treatment area. Partially, processing speeds of up to 100 m/min can be reached. When treating EPDM-/ TPE sections, e.g. the speeds run are about 2 to 30 m/min.
Eltech's has demonstrated in many user operations that its plasma technology can provide superior surface treatments as activation and cleaning than the use of solvent.
Normally it is extremely difficult to pre-treat composites because of the differing electrical and thermal conductivities. In the Eltech’s atmospheric plasma process, low temperature plasma is applied to the material to be activated allowing superior surface treatment without any negative effects on composite materials.
Eltech's plasma systems and nozzles require very little space and are easily installed into existing production lines. We can easily adapt our pre-treatment stations (plasma nozzles within a protective covering ) to your individual manufacturing conditions.
The only operation expenses will result from the electricity and compressed-air consumption, and the ordinary maintenance costs. No costly operating supplies or other consumables are needed.
Plasma is much cooler than other combustion flames (about 300 °C). With most applications, the temperature of the moving material increases by about 15 °C. The process is cool enough that even fingernails can be treated using Eltech’s plasma method.
You need nothing other than electrical energy and oil-free compressed air. If you do not have a separate compressed-air supply, we can provide Air compressors for you.
There is a risk of electric shock directly inside the plasma flame. The nozzles themselves are grounded and therefore can be directed by hand without risk of electrical shock.
The length of time that the activation effect will last will vary depending on the material activated. The effect is strongest directly after the treatment, then fades gradually and settles at a level higher than before pre-treatment. Under ideal circumstances production steps such as coating or painting should be carried out directly after the pre-treatment.However, activation by plasma shows an extreme long-time stability in comparison to other pre-treatment methods. We would be pleased to discuss with you in detail how the activation effect will work in your particular application.
