Perhaps because of the examples of static electricity we learned in middle school-like rubbing a balloon on your hair to get your hair to stick out on the surface of the balloon-the generation of static electricity is often considered a frictional phenomenon. In truth, static charge can be created in two ways: contact and separation. For example, when two uncharged materials come in close contact with one other, the surface electrons of each material tend to migrate, ultimately assuming a different arrangement than they would otherwise possess in the individual materials. When the two materials are then separated rapidly-like when first coming off an unwind station, for instance-the displaced electrons will likely have difficulty redistributing themselves into their normal arrangement. As a result of this separation, one surface may be positively charged and the other negatively charged.
For years, static charges have been considered a cost of doing business in the packaging landscape. However, as the problem has become more pronounced with increased production speeds and higher standards of quality-especially in flexible packaging operations-efforts to control or altogether eliminate this costly problem have likewise increased.
“Some of the unique static charge challenges that flexible packaging faces have to do with the diversity of the substrates, like BOPP, PET, PVC or Mylar,” says Terrance Clark, sales manager for static control supplier TAKK Industries. “And, given their relatively light weight and fast production speeds as compared to corrugated or rigid materials, the range of materials used in flexible packaging can be more heavily impacted by the negative effects of static electricity.”
Clark explains that new flexible packaging materials are constantly being developed and these advancing materials may either ease or exacerbate the static charge conditions that converters face. But no matter the static control challenges these new materials may generate, solving these static problems still rests with tried and true fundamentals.
“Staying on top of static problems really is a matter of identifying the source and cause of static problem, then specifying the appropriate static control solution and its proper placement within the process-an application engineer is a valuable asset in this process,” says Clark. To this end, he explains that static control solutions can be divided into two groups: Passive, which rely on non-electronic means for eliminating static; and active, which require electricity to generate positive or negative ions to mitigate static’s effects.
Examples of passive devices include grounded tinsel or static control string positioned closely to, or even lightly contacting, the web to eliminate static or contaminants, including dust and other small debris. However, passive controls may be ineffective at eliminating all static present in a web and also require regular replacement as they wear out over time.
On the active side, TAKK Industries offers its IonStorm XR2 Static Elimination System, which provides high-performance ionization output and extended ionization range.
“As the web winds or unwinds, it also increases or decreases in diameter; the IonStorm XR2 continuously and effectively neutralizes the static charge of the web with extended range ionization, scanning the static-laden surface up to three feet away,” says Clark. Clark further explains the system’s design lends itself to applications where, due to space constraints, users cannot mount static control devices within an inch or two of the web, or what’s historically been considered the optimum distance for eliminating static.
Clark explains that packaging converters sometimes overlook the importance of static control systems, and believe they're to be used only when users experience a problem. But Clark believes there's a counter to that, and for sensible reasons.
“Every flexible packaging manufacturer will encounter static problems at some time or another and the result of that static problem could be really dire for operations,” explains Clark. “With static being a naturally occurring phenomenon, you can’t really predict when or to what degree it’s going to occur. But you can control having a quality static control system in place, and that can be the difference between completing a job profitably or not.”