Corona discharge treatment an overview sciencedirect topics. Many plastic films have an inherently low surface energy which effects particle adhesion to the substrate. A corona treatment system consists of an electrode connected to a highvoltage source and a grounded roll as shown in figure 1. Surface energy of solid materials and the need for surface treatment of polymers. Corona treatment is conducted by applying a high voltage to small diameter electrode tips. The corona treatment of plastic film is done by passing the film through the corona discharge created between electrode and dielectric covered ususally silicone rubber sleeve earthed roller as shown in. Surface composition analysis of pp films treated by corona. Charging of moving surfaces by corona discharges sustained in air. Corona discharge corona process, corona surface treatment. An electrode with a peak shape is affixed facing the roll, which allows easy generation of the electrical discharge in the air. How surface treatment works corona and plasma treatment tantec.
Electrical characterization of a corona discharge for surface treatment. Corotec corona discharge surface treating systems and. The corona occurs when a high voltage is applied across the electrodes to cause ionization of air. The material that needs treatment is revealed in front of the electronic corona discharge. Corona treatment surface treatment by corona surface. Abstract aluminium and titanium surfaces have been treated by corona discharge in air and gave bonds of strength similar to those obtained by conventional. The aim of this book is to describe the primary polymer adhesion issues faced by manufacturers, processors and converters, to outline a variety of methods for. However, this jet also transmits up to half the discharge power to the plane ref. In pointtoplane unipolar current coronas, as well as in wirecylinder or wireplane ones, space.
Unlike the purely mechanical bond, as in the case of an ink penetrating into a porous surface like paper, plastic films will generally need some means of surface treatment to achieve acceptable chemical bonding with the ink or adhesive. Corona discharge ozone generators can be either air cooled or water cooled. Corona discharge treatment in the presence of air or action of oxidizing mixtures entails substantial morphological and chemical modifications in the surface region of a polymer, such as alteration of external appearance and formation of functional groups 15, 16. Corona is a phenomenon that has the capability for degrading insulators, and causing systems to fail.
The treatment process is an essential part of our production line and provides our clients with a wider range of adhesivefastener capabilities. Corona treatment, corona surface treatment, corona. Key to the success of the discharge is the maintenance of an air gap between the electrodes and the substrate that is. Corona discharge equipment consists of a highfrequency power generator, a highvoltage transformer, a stationary electrode, and a treaterground roll. Water treatment by pulsed streamer corona discharge. Underwater discharge requires additional energy for plasma onset by cavitation, but it has the advantage of a large plasmaliquid contact surface. Occurrence of reverse side effects in corona treatment of. Effect of the electrical conductivities of corona discharge. In either case the excess heat must be safely removed from the corona cell as ozone production will be reduced with excess heat due to the decreasing halflife of ozone as the. In order to reduce the effect of humidity, the corona discharge energy cde value was. In this discussion, formulas are provided to calculate the voltage at which corona occurs, and a mention is made of a useful application for corona. Surface treatment systems are available for virtually any surface format including dimensional objects, sheets, and roll goods that are handled in a web format.
The ozone within the corona reacts with the pp or pe surface. Corona treatment surface treatment by corona surface rycobel. Electrical characterization of a corona discharge for surface. Two different surface treatments have been applied to a synthetic vulcanized styrenebutadiene rubber r1. In comparison with another newly emerging femtosecond laser filamentation method, the snow precipitation induced by the corona discharge has about 4 orders of magnitude higher wallplug efficiency under similar conditions. Part of the polymer science and technology series book series pols, volume 2.
During corona discharge these electrodes are surrounded by a characteristic glow, which is also called a corona or a corona discharge zone. Plasma discharge has a relatively narrow treating width. What is corona treatment by the inventors of corona. A corona treating system is designed to increase the surface energy of plastic films, foils. Corona discharge treatment has been carried out on r1 rubber by varying the electrodesample distance 24 mm, the duration 1 to 11 sec and several parameters in the treatment of r1 rubber with uv treatment lampsample distance between 1 and 5 cm. Wetting is the ratio between the surface energies of the liquid and the plastic material, and is measured in dynecm.
When the computed field value on the surface of the rod tip exceeds the ionization threshold field, the corona discharge occurs, and different directions and speed values of wind can result in different temporal and spatial distributions of corona ions. A corona discharge generator for surface treatment without the use of a stepup transformer with a highvoltage secondary is presented. Fields of this type are formed at electrodes with very large curvature of surface, such as points or thin conductors. Plasma processing for tailoring the surface properties of polymers. Corona discharge is an electrical discharge brought on by the ionization of a fluid surrounding a conductor, which occurs when the strength of the electric field exceeds a certain value. The term corona pretreatment is generally used to describe a highvoltage discharge between an electrode and a counter electrode. Corona treatment is the longest established and most widely used plasma process.
The result is a cloud of ionized air or corona discharge which is then used for the surface treatment of plastics and other materials. This unique selfcontained and portable corona discharge surface treating system is designed for processing a wide variety of materials in either sheetfed or rolltoroll format, and is an ideal platform for doing inhouse testing in order to determine the effectiveness of corona discharge surface treatment on your materials. Spottec a high frequency corona system product video. Therefore, this treatment is drawing attention in the field of new functional materials. By understanding the basic science of corona surface treatment, virtually any bonding problem can successfully solved, even for toughtobond polymeric and elastomeric materials. Though the concept of corona treatment and plasma surface treatment are similar, which makes the difference in their name. As a result, a nonuniform charge patterns may result due to the interaction between the corona discharge and the moving surface. Tappi training course calendar company classroom tappisafe. This causes surface activation of the material by bombarding it with plasma ions.
Corona discharge definition and meaning collins english. Corona discharge definition of corona discharge at. Our electrochemical view of the pointtoplane corona discharge may be summarized by fig. How plasma surface treatment is different corona discharge. Getting started with corona surface treatment enercon. The grounded roll is usually covered with an insulating material such as polyester, ceramic, epoxy or silicon rubber. Corona discharge treatment is the most common method of increasing the energy level of pp and pe materials see below.
The corona surface treatment of plastics before coating, bonding or printing is aimed at improving adhesion. Corona treatment is the solution to this well known problem, said eisby, whose father, verner, was the inventor of the process, and who today runs the international family business with his brother frank. Surface modifications of a vulcanized rubber using corona. Principle of surface modification by coronagas plasma. Quality corona treatment equipment on sale you can find corona treatment equipment from the most reliable suppliers on. Corona treatment is a technology used to process plastic foils on large widths several meters and at a fast pace several hundreds of meters minute plastic foil is mounted onto a supporting roll connecting to the ground. In order to successfully accomplish this the liquid adhesive, or ink should be able to wet the surface of the material. Symposium proceedings of the th symposium on application of plasma processes, ed. Corona discharge treatment cdt is a surface modification technique commonly used to treat plastic films prior to adhesive bonding, printing with inks, lamination to other films and other coating applications. Electrical discharge in water treatment technology for. Corona vs plasma treatment what is the difference 3dt. Mdpe, and their 8020 blend were studied by different techniques after corona. Extended treatment for several seconds appears unnecessary and instead is likely to cause some ablation and ultimately surface roughening 11. In this study, the treatment conditions are, in energy terms, representative of those used in industrial and laboratory coating.
This process uses an electric current to create an ozone generating spark a corona. By treating the material with a high frequency corona discharge, its surface becomes much more impressible to adhesives, inks and coatings. That changed when plasma and corona was discovered. Surface treating, corona treating units by sicatech from. The basics of corona treatment watch our video here. One measure of wettability is the surface tension, which on smooth surfaces such as foils can be reliably and easily determined with test inks. Corona treatment is a widely used surface treatment method in the plastic film, extrusion, automotive and medical industries. Request pdf corona treatment this chapter describes a method of polymer. Corona treatment is the most common surface treatment to increase polymer dyne levels in the.
We invite you to learn how corona treaters work or download our getting started with corona treating e book. This causes a corona discharge to be created which is a visible plasma curtain that has the ability to partially. Corotec corporation is an internationally recognized supplier of corona discharge surface treating equipment and accessories, serving numerous customers around the globe. Corona discharge and ultraviolet radiation treatments have been used as environmental friendly alternatives to the common surface treatment of halogenation for a styrenebutadienestyrene rubber. Practical interest in the surface discharge is manifested not only as a negative phenomenon in highvoltage technology 4, 5, also surface discharge can be used to construct an effective earthing 2. Surface characterization of plasma treated polymers for applications as biocompatible. This phd thesis has been a first basic investigation of corona discharge with brush type discharge electrodes. Corona discharge treatment cdt is a surface treatment technology that uses an electrical discharge to oxidize the surface of polymer film. Corona discharge definition of corona discharge by the free. Corona and its effects evan mayerhoff high voltage connection, inc. The presence of oxidized polar groups on the film surface, mainly, co, co and coh, was confirmed by infrared spectroscopy ftiratr and atomic force microscopy afm revealed a dramatic change in the morphology and provided qualitative results of the. Consequently, a substance placed under the corona discharge are impacted by the electrons with energy two to three times that necessary to break the molecular bonds on the surface. In the corona discharge process the surface of substrate is bombarded with highspeed electrons. Influence of a corona treatment on a plastic surface.
Corona discharge definition, a discharge, frequently luminous, at the surface of a conductor or between two conductors of the same transmission line, accompanied by ionization of the surrounding atmosphere and often by a power loss. High energy corona discharge effectively severs molecular bond chains on the surface of the material. This ionized air corona discharge can now be used for the surface treatment of a wide number of materials which show poor or no adhesion properties to media such as printing inks, adhesives, etc. When a surface undergoes corona treatment, it passes under a corona discharge. The corona discharge, its properties and specific uses. The ozone within the corona reacts with the pp or pe surface to raise the energy level. Corona treatment affects only the surface layer of the plastic, to a depth of 0. Surface treatment of polypropylene by corona discharge and. Sample pages plastic surface modification surface treatment. Spottec a high frequency corona system product video youtube. Sicatech is an innovator in the designing and building of specialty 3d corona treating system aka corona discharge pre treatment or corona discharge surface treatment systems. Corona treatment is a surface modification technique that uses a low temperature corona discharge plasma to impart changes in the properties of a surface. Corona treating systems are used to raise the dyne level on a variety of plastics and other substrates. The corona plasma is generated by the application of high voltage to an electrode that has a sharp tip.
It arises in highly inhomogeneous electric fields in the vicinity of one or both electrodes. Polypropylene films pp surface treated by corona discharge in air was analyzed to verify the changes on surface composition. Surface discharge is used for water purification with streamer corona technology 6. The corona treatment is obtained by creating an electric discharge with high voltage and high frequency in a limited air gap 1 or 2 mm, both linear and uniform, between an electrode charged to high voltage via a power generator. Corona discharge is probably the most widely used industrial surface treatment for polyolefin films 1, 4.
The corona treatment method is widely used nowadays to increase the surface tension of the films. A corona discharge is an electrical discharge brought on by the ionization of a fluid such as air surrounding a conductor that is electrically charged. Corona discharge can be used for surface treatment due to production of neutral species that include ozone and nitrogen oxide, which improve adhesion. The corona discharge 55 along the field lines and that field lines ending outside 0 65 usually originate on the point surface outside the ionization region. Corona discharge treatment for medical surface preparation.
How plasma surface treatment is different corona discharge treatment. Enercon has an international reputation for innovative and reliable corona treating systems. Corona discharge article about corona discharge by the free. Corona discharge surface treater without high voltage transformer. In electricity, a corona discharge is an electrical discharge brought on by the ionization of a fluid surrounding a conductor, which occurs when the potential gradient the strength of the electric field exceeds a certain value, but conditions are insufficient to. Surface treatment of polypropylene by corona discharge and flame. The most basic measurement used to address this question is called watt density w d. This reaction is initiated by highenergy electrons in the discharge gap, which cause. To obtain optimum adhesion, it is crucial that the surface energy of the substrate is equal or higher than the surface energy of the material to be applied to the polymer. Corona discharge treatment is commonly used to improve the wettability, adhesion, and biocompatibility of a.
The effects of wind on the diffusion region of corona charges. Avoiding adhesion problems corona treatment is a high frequency discharge that increases the adhesion of a plastic surface. Corona treatment is a plasma surface treatment that is often referred to as air plasma. It is shown that n2 apgd treatment leads to a higher surface energy than air corona treatment, and to the formation of mostly amine, amide, and hydroxyl functional groups at the polypropylene surface. The most advanced and successful methods of surface treatment are based on a principle of high voltage discharge in air, a principle also know as the plasma cleaning principle. Corona treatment ensures the surface energy of the plastic is higher than that of the liquid by increasing the adhesion of the plastic surface. Pvc treatment by corona discharge in helium modifies surface characteristics such as morphology. They are created by applying a high voltage to small electrode tips. Basics of high voltage discharge in air and its application to surface treatment. Neuware application of corona discharge in offgas and wastewater treatment includes the basic investigations to model the currentvoltage characteristics, ozone generation and uvradiation with brush type discharge electrodes. Corona discharge effectively improves the surface tension on numerous materials that show poor or no adhesion properties to media such as printing inks and adhesives. Getting started with corona surface treatment this free ebook shares expert insights from surface treating experts.
Corona phenomenon takes place when a high voltage is applied across electrode and grounded metal roll to induce ionization of air. To obtain optimum adhesion, it is crucial that the surface energy of the substrate is equal or higher than the surface energy of the. Deco tech is the exclusive north american distributor for sicatech of denmark. Corona discharge is characterised by bright filaments extending from a sharp, highvoltage electrode towards the substrate. Plasma enercon receives many questions about the differences and similarities between corona and plasma surface treating. It is often necessary to bond plastic materials to metals or other plastic materials, or simply print on a plastic surface. Surface treatment of metal surfaces by corona discharge. Tappisafe finally a standardized approach to safety for the entire industry. In all cases, the context of the question is very important as some industries have adopted unique definitions of each term. Gain a great understanding of the corona treatment theory.
In this paper, we discuss results from a computational investigation of a dc blade corona discharge sustained in. A method to corona treat a polymeric surface with a fixed and preset treatment energy level is proposed. The electrical discharge causes the air in the electrode gap to ionize. Corona discharge surface treatment is an effective and efficient process that is commonly used to increase the surface tension of a wide variety of materials, parts, and packaging in order to provide a surface that is more receptive to inks, coatings, or adhesives. Corona discharges are usually a glowing purple veil that is used to alter the adhesion properties of surfaces. How surface treatment works corona and plasma treatment. Corona treatment increases the bonding characteristics of a substrate by increasing the surface energy dyne level. Atmosphericpressure plasma treatment in gas enables provision of selectivity to the type of functional group and increasing radicals on the surface. This book will provide the answers to the following questions. Electrical characterization is based on a display of voltage and charge which. Corona treatment sometimes referred to as air plasma is a surface modification technique that uses a low temperature corona discharge plasma to impart changes in the properties of a surface. The attraction of using flame treatment as opposed to corona discharge. Spontaneous corona discharges occur naturally in highvoltage systems unless care is taken to limit the. Surface treatment by corona or atmospheric plasma discharges are.
Improvement of corona discharge model and its application on. Corona and plasma the different worlds of surface treatment. This chemical change increases the surface wettability and promotes the adhesion of subsequent coatings. Spontaneous corona discharges occur naturally in highvoltage systems unless care is taken to limit the electric field strength. Plasma discharge has a relatively narrow treating width but is capable of imparting enormous surface energies onto substrates. For industrial applications short corona treatment times are required for commercial viability.
The oil bath for highvoltage components is eliminated and. To obtain good adhesion to materials that have a low surface energy i. Can you offer any general guidelines on the relationship between corona treater power output and dyne level increase. This is a low temperature process that is able to modify surfaces and increase their surface energy. To be more precise, corona treatment is used to increase a materials surface tension in an effective way. Whether a liquid wets a material well or poorly primarily depends on the chemical nature of both the liquid and the substrate. Morphological and chemical changes of the surface of low. Although there are numerous theories explaining the principles behind the process of corona treating, the most commonly accepted theory appears to be the.
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