Final Decision to Certify Hazardous Waste Environmental Technology
Airco Coating Technology's Surface Treatment System
Certification No: 95-01-015
Airco Coating Technology (ACT), a division of the BOC Group, Inc., manufactures the PS0350, PS0500, and Hammer II cold gas plasma systems for surface cleaning of various plastic and metallic parts, and altering the surface chemistry of various plastic parts. As a Pollution Prevention technology, these systems are used to replace solvent based systems for surface cleaning or treatment of parts thereby reducing or eliminating the generation of hazardous waste and/or toxic air emissions associated with the use of solvents.
Gas plasma technology is a process where common or inert gases such as air, oxygen, helium and argon are partially ionized by radio frequency (RF) energy to create a plasma at close to ambient temperatures. Plasma is a partially ionized gas containing ions, electrons, and various neutral species. Each process gas used produces a unique plasma chemistry. The plasma contains highly reactive positive and negative ions and free radicals that react with organic contaminants or organic polymers (i.e., plastics). The complete systems as manufactured by Airco include a process controller, a reactor chamber, a RF generator, an automatic impedance matching system, a vacuum pump, and a gas control module. Parts to be cleaned or treated are placed in the reactor, a vacuum chamber, in a batch operation. Low flow rates of the selected process gas are subjected to RF energy to create a plasma within the reactor. Process gas flow rates vary depending on the specific system, ranging from less than 1 liter/minute for the PS0350 and PSO500, and up to 10 liters/minute for the Hammer II. The gas plasma within the reactor is maintained at near ambient temperature (bulk gas temperature) and maintained under vacuum conditions (e.g., 100 to 500 millitorr).
The gas plasma reacts with the organic surface contaminants or plastic surface materials of the parts being treated. Ionized gases recombine to their original gas form as they exit the reactor along with reaction products formed during the treatment process.
Process gas composition, pressure and flow rate, and parts residence time are the critical parameters controlled for each specific application. The physics and chemical reactions occurring in plasmas are very complex and not fully understood. Depending on the process gas used and the composition of the part being treated, various chemical reactions can occur with resulting off-gas emissions. Reaction products in the emissions can potentially be toxic, corrosive, or flammable. However, because of the low process gas flow rates for these systems, the relative volumes of these contaminants are small and can be controlled. Depending on the specific application, the emissions generated by the plasma process may require controls to capture or treat contaminants of concern to an acceptable level.
ACT Surface Treatment Systems can be used to remove organic surface contamination from surfaces of plastic and metal parts, or to modify or enhance the physical and chemical characteristics of the surface of polyester and polypropylene plastic parts to improve their bonding and adhesion properties. After plasma treatment, plastics typically can be bonded, coated or painted without the use of toxic, solvent-based cleaning processes. In certain cases, the chemistry of the plastic surface is modified or enhanced to allow the plastic part to be painted or coated without an adhesion promoter pre-coating. DTSC’s findings are described in greater detail in an evaluation report.
A copy of the published Certification Notice may be obtained by contacting us at:
File last updated: October 9, 1996