19. November 2012   7:56 pm
Andy Stecher

Andy Stecher
Elgin, IL

Hello again,

My last blog entry emphasized the need for a clean glue flap in the manufacturing/gluing of folding cartons.   This entry describes how a perfectly clean glue flap (plasma cleaned) combined with plasma activation/surface functionalization add up to successful adhesion results.

Plasma activation refers to the modification of a polymer surface by highly reactive oxygen ions present in a plasma.   These ions allow for the formation of oxygen based functional groups (primarily hydroxyl – OH) on the top surface of the polymer.   The addition of these groups results in an increase in surface energy and surface tension.   The surface also becomes polar allowing for greater wettability  – in real world terms, the glue will spread and impinge on the surface completely, making intimate contact with the surface.

Oxygen based functional groups on the surface act as bonding sites for adhesives.    Increased polarity and intimate contact between the adhesive and substrate can result in a decrease in adhesive consumption.    The activation allows for true covalent bonding between the adhesive and substrate resulting in a far more robust bond than would otherwise be achieved.   This is particularly helpful when gluing frozen food cartons or other cartons that can experience large temperature variations.   If a true chemical bond is not achieved between adhesive and substrate, cartons exposed to freezing temperatures especially, can pop open due to the adhesive becoming brittle and cracking at low temperatures.

In summary, plasma activation is absolutely essential in the folding carton industry to ensure repeatable, reliable bonding across all product lines in any manufacturing facility.

My next entry will discuss cost savings and ROI as it relates to plasma treatment in the folding carton industry.

Thanks for your time and attention.

Shaun Glogauer.

13. November 2012   6:44 pm
Tim Smith

Tim Smith
Ancaster, Ontario

Our plasma generators need two utilities in order to run; electricity and air.

In order to achieve maximum life and maximum performance for a plasma system, the air supply must be free of dirt particles as well as oil and water. The air supply needs to be filtered to a level equal or less than 0.3um. This can be readily accomplished using a three stage filter system.

Particulate suspended in the air will act like sandblasting to the jet nozzle causing excessive wear.
Water, in its liquid form, not humidity, will cause thermal shock which will damage the ceramic insulator in the jet. The air does not have to be dried, but, as mentioned, it cannot have liquid water present in it.

Any oil in the air supply will have seriously negative, and possibly dangerous, results. Introducing highly atomized oil into an arc may result in ignition of the oil within the jet. This could result in a fire which would quickly spread to the entire work cell. In the event that the oil does not ignite, you still have the problem of trying to clean and activate a surface that you are now coating with oil.

So by keeping the air supply to the plasma system clean, you can extend the life of your plasma jets and help ensure the proper results from the plasma treatment.

Till next time,