Wonder how corona treating works and what it really does to surface of your substrate? We've answered these questions and a few others that we are commonly asked.
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Can all types of substrates be treated on either a bare roll, covered roll, or universal roll system?
No. Covered roll system can only treat non-conductive substrates. Bare roll or universal roll systems can treat both conductive and non conductive substrates.
What is the difference between a covered roll treater, bare roll treater and a universal roll treater?
The difference between the two systems relates to where the insulator is in the treating station. In a covered roll station the roll is insulated with some type of dielectric material and the electrode is bare metal. In a bare roll system the roll has no insulation, but the electrode is insulated. In a universal roll station both the ground roll and the electrode are insulated.
What does corona treating do to the surface of converting films?
Corona treating forms low-molecular-weight (LMWOM) on film surface; oxidizes film surface; and forms positive and negative sites by adding and deleting electrons.
Corona is ionized air created by discharging high frequency high voltage energy across a metal or insulated electrode. This electrode is positioned over a grounded roll. The space between the electrode and the roll is typically .060". It is in this air gap that corona is generated.
Dyne level is a unit of measurement used to determine the surface energy of (in our industry) the surface of a films or foils. Most polyolefin films have low dyne levels some where between the high twenties to low thirties. In order to be able to convert these films, the surface tension will need to be between the high thirties to mid forties. Corona treating is used to accomplish this increase in dyne level. How does your application stack up? Visit our recommended treatment range matrix.