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How Treaters Work

What Is Corona Treatment, and What Is It For?

Put simply, corona treatment is a technology which alters the surface of plastics and other materials so that they can be printed on. Due to the nature of these materials, they do not easily bond with inks, coatings, adhesives, and other printing materials. Corona treatment makes changes to properties of these materials so that they have higher “surface energy,” allowing inks and other materials to readily adhere to the surface of the material. 

A common example of a corona treated product is your classic plastic shopping bag. When you see a plastic shopping bag with a store logo or anything else printed on it, that printing was made possible by corona treatment. 

In addition to plastics, other materials that can be corona treated include:

  • Paper
  • Metals and foils
  • Foams
  • Woven and nonwoven fabrics

How Corona Treaters Work

The corona treatment process works by applying a high voltage electric discharge to an electrode across an air gap. This creates what is known as a “corona discharge.” This discharge ionizes the air around the material, causing changes to it on a molecular level and increasing the material’s surface energy. 

The corona treatment process occurs in a matter of seconds to minutes. A number of theories exist as to what is happening to the material on a molecular level, including oxidation and micropitting. Although these changes are invisible to the naked eye, they significantly increase the ability of inks and coatings to adhere to the material.


Components of a Corona Treatment System

A corona treatment system consists of two main parts: the power supply, and the treater station.


Corona Treater Power Supply

The corona treatment station power supply consists of a high frequency generator and a high voltage output transformer. The supply takes power, converts it to a higher frequency and voltage, and provides the treater station the power needed to generate a corona discharge. Power supplies range in power rating from 500 watts to 30 kilowatts, with the exact wattage needed depending on the application. 


Corona Treater Station

The treatment station is where the corona treatment process actually happens. 

Here, an electrical discharge supplied by the power supply passes from a high voltage electrode to a ground electrode. The bare or covered ground electrode is in what is known as the “ground roll.” This electrode spans the length of the ground roll. It receives the high voltage required to create the ionized air that makes corona treatment work. The material being treated then passes through the ionized air, altering the surface energy and allowing for easier printing, laminating, and more.

Types of Ground Rolls

The ground roll in a corona treatment station is either covered or bare, depending on the application.


Covered Roll

Covered rolls have a dielectric covering on the ground roll, while the high voltage electrode in the treatment station is bare metal.  Covered roll systems are used to treat non-conductive surfaces, such as plastic, as this yields the highest efficiency. Covered rolls cannot be used for metallized substrates.


Bare Roll

Bare roll systems have a dielectric covering on the systems high-voltage electrode, while the ground electrode is bare metal.  Bare roll systems are required to treat metallized and other conductive substrates. Bare rolls are also easier to replace, but are limited to a max 130” treat width.


Sizing And Selecting Your Corona Treatment System

The Pillar Technologies team will work with you to build and size the right corona treatment system for your applications. Using our own charts and formulas, we will determine the needed watt density and “dyne level” (a measure of surface energy) required for your facility’s needs. With this information, we will be able to calculate factors such as the size of electrodes, the size of the power supply, and other key info to build a corona treatment system that’s right for your application. 

For a complete article on how corona treatment works, see the Corona Theory article in our web site. To determine how much power your process requires, please see the Size My System Page.

If you’re interested in a Pillar Technologies corona treatment system for your facility, or if you have any further questions, don’t hesitate to contact us