Understanding Plasma Treatment
Plasma surface treatment has become more prevalent in the converting industry than ever before. Plasma is one of the four fundamental states of matter. It consists of a gas of ions – atoms which have some of their orbital electrons removed – and free electrons. Plasma can be artificially generated by heating a neutral gas or subjecting it to a strong electromagnetic field to the point where an ionized gaseous substance becomes increasingly electrically conductive. The resulting charged ions and electrons become influenced by long-range electromagnetic fields, making the plasma dynamics more sensitive to these fields than a neutral gas.
Processes like Corona Treatment, Gas Atmosphere Plasma, Flame Plasma, Atmospheric Pressure Plasma, Low Pressure Plasma, Vacuum Plasma, Glow-discharge Plasma, and Plasma Etching are mechanisms by which plasmas are employed to modify surfaces. Each of these methods are distinctly different, and are chosen based on the desired surface effects. System differences include cost, size, safety, and results. All are very important, however the most significant determining factor in making your decision is using the correct method to get the results you need. Too often, purchasing decisions are made to save cost, or to fit into existing space, only to discover that the equipment does not achieve the results for which it was originally intended.
The corona treatment process is at the simple end of the plasma scale, and is a lower cost alternative for treatment of many plastic films, foils, papers, etc. to enhance the adhesion to other materials by increasing surface energy. If the desired surface qualities go beyond what a normal corona discharge system can provide, another plasma technology should be considered.
Material selections are usually based on the primary engineering properties required for the end product. Unfortunately, critical surface improvements to these materials are sometimes sacrificed. Designers must carefully balance their selection of specially formulated and expensive materials or material combinations to achieve the desired properties that they require. In many cases, the materials which provide the desired surface properties lack some of the primary properties that they desire. This often requires the use of expensive multilayer constructions, or in some cases abandonment of potential products due to the high cost associated with these engineering requirements. One alternative solution is atmospheric pressure plasma technology. This type of surface modification system can provide desired material surface characteristics without sacrificing the primary performance characteristics of the material. This technology (our Protean1™ technology) is capable of altering the surface of a material at a depth of only a few angstroms, yet yielding a profound improvement in material surface adhesion for an unlimited number of applications. Desired effects such as bond strength, superior adhesion characteristics, and chemical reactivity, along with micro thin coating deposition by plasma polymerization, can be achieved.
The use of atmospheric pressure plasma technology is growing quickly as the demand for greater adhesion strength and higher productivity levels increases, and the complexity of flexible packaging constructions grows.
Rory Wolf – Business Unit Manager