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A Simple Guide to Choose a Covering for your Corona Treater

Plastic films are non-porous and generally have low surface tension. Coatings, Inks, and adhesives do not readily wet out or adhere. Corona treatment increases the surface energy of these materials in a uniform and not tangible way to the eye.

A corona treater station for treating polymer films consists of a high-frequency and high voltage power supply or generator, a linear electrode, and a grounded Corona roller with a small air gap between the electrode and the roller. The corona discharge propagates from the electrode to the film surface. 

Coverings Used For Corona Treater Rollers

Dielectrics used on the grounded metal roller include silicone rubber, CSM rubber, glass, epoxy and epoxy/fiber composites, and ceramic. Some of the first dielectrics used on Corona treater rolls were CSM and silicone rubber before epoxy coverings were introduced to create the grounded roller cover more durable.

While ceramic and glass are similar in their resistance to oxidation and the ability to bear more wattage, there are some crucial differences between them. Compared to ceramic, glass has lower impact resistance and lower thermal conductivity and is more readily damaged by static electricity. While silicone rubber, CSM, and epoxy are considered the more affordable choice, it is essential to remember that these three options are all subject to repeated chemical attacks by the same corona that is treating the film.

Glassteel Coatings, formerly known as Empire Treater Rollers, reveals the development of three new coating formulations for both roller and non-roller products. These new Glassteel coatings have been developed to substantially enhance corrosion resistance, release, and heat transfer qualities while maintaining longevity and durability, which are the hallmarks of Glasteel coatings.

Which Roller Covering is the Best?

All roller coverings can deliver excellent treatment levels and uniformity if the corona system is tuned correctly and maintained, but each type has limitations. CSM, silicone, and epoxy coverings are typically low in cost and produce satisfactory results for most applications. Epoxy is much more resistant to scratches and abrasions than the others, but they all can be attacked by oxidation of the corona. Corona power levels are pretty limited because the materials are not thermally conductive. 

High line speeds or difficult-to-treat materials may need power levels above what silicone, CSM, and epoxy can safely handle. Ceramic and glass coverings can handle double the power levels if the rollers are air-cooled and four times the power if water-cooled. Some technical people feel that ceramic also produces a more uniform charge density in the corona because of its relatively high capacitance. 

Deciding which of the covering materials is best depends on your application's specific requirements and demands. If several coverings work, then the expenses and benefits of each have to be evaluated. However, your choices are often limited to particular applications that require specific properties to be met. Other times, the options are limited, with particular applications requiring particular properties. 

If you are willing to increase productivity and efficiency, Empire Rollers & Coatings has solutions. This company has the best skills and knowledge to know your business and needs to create the best-customized roller for you.