Organic thin films from novel plasma processes for improved adhesion of composite materials

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Several industrial processes involving polymer films include a surface activation step based on an atmospheric pressure cold plasma (an ionized gas produced as an electrical discharge). They involve devices commonly know as "corona" or "dielectric barrier discharge" treaters which create reactive chemical species by ionizing air. These species can react with polymer surfaces resulting in the covalent bonding of polar functional groups to the surface. Such processes can promote the wetting of polymer surfaces with water or polar solvent based paints and glues, which would otherwise be difficult to apply homogeneously. Due to the constraints associated with industrial plasma processes at atmospheric pressure, these have seen little significant improvement over the last decades. In recent years, atmospheric pressure plasma technology has been a very actively researched field and several developments are now ripe for industrial application. Our laboratory has been developing thin organic coatings deposited by atmospheric pressure plasma technology for various applications and now has a wide array of methods for depositing various types of coatings. Of particular interest are coatings deposited from highly diluted ethylene in nitrogen or air, a mixture that is both relatively inexpensive and non-toxic. In an initial collaboration with our industrial partner, CGT inc., we investigated the use of plasma deposited organic coatings to improve two of their processes: : i) lamination of polypropylene foam to polyvinyl chloride films and ii) application of a top finish polyurethane coating to thermoplastic olefin film. While we were unsuccessful in achieving the first objective, we were successful in preparing organic coatings that would successfully promote the adhesion of the polyurethane top-finish. Those coatings were however deposited by a low-pressure plasma process that would be expensive to implement in CGT's production line. This project aims at developing an atmospheric pressure plasma method to prepare coatings analogous that were found to perform well. A successful development would give our partner a clear competitive advantage.