We receive many questions from customers when researching surface treatment solutions for their converting lines. In this blog post we highlight a few of the most common questions we receive.
How Does Corona Treatment Work?
Although there are numerous theories explaining the principles behind the process of corona treating, the most commonly accepted theory appears to be the theory of high speed oxidation. This theory states that the energy of the corona breaks the molecular bonds on the surface of the non-polar substrate. The broken bonds then recombine with the free radicals in the corona environment to form additional polar groups on the film surface. These polar groups have a strong chemical affinity to the polar inks and adhesives, which results in improved adhesion. Similarly, the polar surface results in an increased surface energy which correlates with improved wettability.
What Must Converters Do To Keep Their Corona Treating Equipment At Optimum And Consistent Operating Levels?
To keep Corona Treating Equipment at the most optimum operating levels users should continue with the scheduled maintenance as instructed within each equipment manual:
- Inspect and maintain cleanliness of both the ground roll(s) and electrode(s)
- Eliminate broken web or loose substrates near the exhaust capture ports of the station and inspect all high voltage connections.
- Assure proper exhaust/cooling air to eliminate issues associated with fugitive ozone emissions.
What Other Problems Can Arise During The Corona Treating Process? How Can They Be Addressed?
Inadequate exhaust ductwork design can cause problems in the corona treating process. A faulty exhaust system design has the tendency to provide far more static pressure on the exhaust fan than desired. The result of this is reduced air volume exhausted from the treater station itself. This in turn does not trap and capture as much of the ozone generated in the corona treating process as needed, but merely allows it to escape out and around the station itself; thus not removing it from the workplace. Also, users should assure that the final exhaust point of the ozone is exhausted at least 10’ above any roofline and is not exhausted near any fresh air or make-up air units.
How Do I Determine The Right Watt Density For My Application?
Based on our 40 years of experience, we have charts that will help estimate the right watt density for your application. If your material is rare, or if you wish to test the watt density, contact your Pillar Sales Representative to schedule a sample run on our line. This way, you will know the exact watt density for your application and ensure your system is neither over sized nor under sized. Take a look at these charts here.
What Can Be Done To Avoid Over-Under-Treating Substrate Surfaces?
To establish a continuous quality product, assure that the resins are added in proper proportions prior to extrusion.
- Purchase quality resins and train your plant personnel to note the need for a change in the power levels of the corona treater power supply.
- Begin your process by establishing a beginning point for the power level and work your way up on power until the anticipated dyne level is achieved; this being done through QA dyne checks of the film.
- Once the power level is established for the given product at the given speed, note the power level to re-use the next time, and you are assured of desired dyne repeatability.
For more frequently asked questions or more information on Corona Surface Treatment, visit www.pillartech.com.