Atmospheric Pressure Plasma Treatment: Enabling Environmentally Friendly Surface Treatment Processes

This paper will outline the basic premise of surface treatment requirements, introduce the concepts of plasma and plasma treatment, describe the effects of plasma treatment, detail the environmental benefits of plasma via case studies and end with a short summary. A quick introduction of current surface treatment methods will be discussed and compared with plasma treatment. Competing technologies include flame and corona treatment. A short overview of plasma and how it is generated and used in an industrial setting will be explained. Atmospheric pressure plasma (as opposed to low pressure or vacuum plasma) is created by exposing a process gas to a high frequency, high voltage electric discharge that excites electrons and induces them to leave their orbits, creating simultaneously free electrons and ions, and thus a plasma. The effect of plasma treatment on substrates and bonding parameters will then be discussed. This treatment must produce clean and highly activated surfaces with reliable and repeatable characteristics in order to achieve optimal adhesive bonding, coating, and printing results. The remainder of the paper will focus on the elimination of environmentally unfriendly surface treatment processes such as: solvent wiping, power washing, and the application of adhesion promoters and primers. These will be demonstrated through the use of several case studies including the potential elimination of both power washing and application of adhesion promoter to plastic parts prior to paint applications, as well as the elimination of harsh cleaning chemicals prior to coil coating processes. Plasma treatment can not only eliminate wet chemistry applications, but also improve adhesion properties and the quality of finished parts, reduce energy consumption, and streamline the manufacturing process resulting in both environmental and cost benefits.