FAQ
CORONA TREATER
What is Corona Treatment ?
In corona treatment, the film is passed over the roller through the air gap between the fixed electrode and the dielectric whereby the film is exposed to a very high voltage potential at a very high frequency, which causes ionization of air. The equipment used to achieve this comprises a generator, which converts available 230V / 415V, 50Hz power supply a high voltage transformer and the treating station itself.
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.
How do you size a Corona Treatment system ?
How do you determine the generator power required ?
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.
What are the consequences of Over/Under Treatment of the Film ?
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.
How can dyne level of the Treated/Non-treated Substrates be determined ?
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.
What is the acceptable treatment level for good printing ?
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.
What is Back Side Treatment? How can it be avoided ?
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.
Is web tension essential in corona treatment application ?
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.
How can a Corona Treater be maintained ?
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.
What is 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.
what is the power consumption ?
Approximately 1 kw power is required.
Can I treat 3 dimensional shaped parts with plasma ?
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.
Will Plasma surface modification alter the mass of the parts treated ?
No, the mass of your parts remains unchanged.
Can I partially Plasma treat a surface ?
Yes, any part of the surface can be masked to shield it from the effects of the plasma.
How fast can I treat with Atmospheric Plasma nozzles ?
Typical treatment speeds of up to 30m/min are common, for higher speeds additional nozzles can be added.
Can I clean surfaces with Plasma ?
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.
What temperature does Plasma operate at ?
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.
Does Atmospheric Plasma produce any bi-products ?
Unlike corona treatment Atmospheric Plasma does not produce any ozone.
Does Atmospheric plasma require any special gases ?
No, Atmospheric plasma simply requires an oil-free and dry compressed air supply and a standard 230V 13 Amp electrical supply.
How close to the surface should I position my Atmospheric Plasma nozzles ?
Typically between 8 - 20 mm, depending on the materials to be treated and the required treatment levels.
What is Plasma Cleaning ?
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.
What is Cold Plasma ?
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.
What are the main advantages of “Eltech’s “ plasma technology in comparison to other surface treatment methods ?
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.
What will you need to run a plasma pretreatment system ?
Public current (230V/400V) as well as a compressed-air supply are sufficient.
What are the possible production speeds that can be reached ?
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.
Can original methods (use of solvents) be replaced by the Eltech’s plasma technology ?
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.
Why is it that the plasma surface technology works so well for composites ?
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.
Why is it so simple to integrate your plasma systems into production lines ?
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.
What kind of running costs will arise ?
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.
Are plasma flames hot ?
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.
Does the plasma process produce any toxic emissions ?
No.
Are any special gases required for the Eltech’s plasma process ?
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.
Is there any risk of an electric shock in the area of the plasma beam ?
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.
How long does the activation effect on the surface last ?
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.
What is Static Electricity ?
Static electricity is defined as an electrical charge caused by an imbalance of electrons on the surface of a material. Static electricity is defined as an electrical charge caused by an imbalance of electrons on the surface of a material.
What is static electricity with example?
An electrical charge that accumulates on an object when it is rubbed against another object — for example, the spark that jumps from someone's hand to a doorknob after the person has walked across a rug.
What are 3 examples of static?
Have you ever rubbed a balloon on your head and made your hair stand up? Have you ever walked across the carpet in your socks and received a shock from a doorknob? These are examples of static electricity.
What is the difference between current and static electricity?
The most significant difference between the static electricity and the current electricity is that in that static electricity the charges are at rest and they are accumulated on the surface of the insulator, whereas, in current electricity the electrons are in state of motion inside the conductor.
hat are the 3 laws of static electricity?
Based on the same types of experiments like the one you performed, scientists were able to establish three laws of electrical charges: Opposite charges attract each other. Like charges repel each other. Charged objects attract neutral objects.
Can static electricity kill you?
Static electricity can't seriously harm you. Your body is composed largely of water and water is an inefficient conductor of electricity, especially in amounts this small. Not that electricity can't hurt or kill you.
Is static charge AC or DC?
The difference between the two is based simply on whether the electrons are at rest (static) or in motion (dynamic). Static electricity is a build up of an electrical charge on the surface of an object. It is considered “static” due to the fact that there is no current flowing as in AC or DC electricity.
Does static electricity have current?
Static electricity is named in contrast with current electricity, which flows through wires or other conductors and transmits energy. The familiar phenomenon of a static shock - more specifically, an electrostatic discharge - is caused by the neutralization of charge.
Can human body generate electricity?
The elements in our bodies, like sodium, potassium, calcium, and magnesium, have a specific electrical charge. Almost all of our cells can use these charged elements, called ions, to generate electricity.
Why do I have a lot of static electricity in my house?
Static increases when the air gets cold and humidity drops. To stay warm in your home, you turn up the heat, further adding to a decrease in humidity and increasing static.
Is static electricity safe?
Static increases when the air gets cold and humidity drops. To stay warm in your home, you turn up the heat, further adding to a decrease in humidity and increasing static.
Do humidifiers help with static?
Moisture in the air prevents static electricity from building up, and that's where humidifiers come in. Maintaining an optimum humidity level around 30 or 40 percent can significantly reduce static electricity.
Can you see static electricity?
Static electricity can produce sparks bright enough to see them in daylight. It can certainly produce sparks visible in a dark room when there is relative motion between things in contact.
Can static cause a fire?
Static Electricity Fire Hazards. Static electricity can generate sparks, and sparks could cause an explosion in the wrong setting. However, this charge must be energetic enough to start a fire. If the spark touches dust, fumes, or other vapors, that can be enough to cause a fire.
Is a static charge permanent?
Static electricity is an imbalance of electric charges within or on the surface of a material. The charge remains until it is able to move away by means of an electric current or electrical discharge.
What happens when static electricity is released?
Static electricity is the result of an imbalance between negative and positive charges in an object. These charges can build up on the surface of an object until they find a way to be released or discharged. ... The rubbing of certain materials against one another can transfer negative charges, or electrons.
