Primers for Bonding Polyolefin Substrates with Alkyl Cyanoacrylate Adhesive

Abstract

Abstract Polyolefins, such as polypropylene and polyethylene, are among the most commonly-utilized plastics in the world, but, because of their non-polar surfaces, are among the most difficult to bond with adhesives. A surface treatment is required before adhesive application to achieve good adhesion. Alkyl cyanoacrylates are widely used instant adhesives, e.g. Super Glue®, for bonding a variety of substrates, such as metal, plastics, glass, wood, and leather. It would be desirable to bond polyolefins with these adhesives because of their availability and ease of use. Amines and ammonium carboxylates, possessing long alkyl chains, were evaluated as adhesion promoting primers for alkyl cyanoacrylate adhesives on polyolefins. Among trialkyl amines, trialkylammonium carboxylates, and tetraalkylammonium carboxylates, trialkylammonium carboxylate primers produced an adhesive bond so strong that the failure occurred at the polyolefin substrate. Trialkylammonium carboxylate primers also demonstrated excellent performance retention over prolonged atmospheric exposure prior to application of the adhesive. Trialkyl amines and tetraalkylammonium carboxylates also promoted adhesion but lost maximum effectiveness on exposure to the atmosphere. The cause of the deterioration in amine primer effectiveness over prolonged exposure was identified to be trialkylammonium bicarbonate formation and/or diffusion of the primer into the polyolefin surface.