An Overview of Thread Locking Adhesives Containing Microcapsules Filled with Reactive Materials

Typically, equipments and devices that are subject to vibration or continuous movement such as cars usually are faced to loose or unplugged metallic joints, which causes metal joints not to function properly and further intensive damages can be occurred. One of the methods to enhance metallic joints is the use of thread locking adhesives. thread locking adhesives not only prevents the metal fittings from loosening, but also by filling the gap between metal fittings, prevents the penetration of oxygen and moisture into them and delaying the occurrence of corrosion. These adhesives contain microcapsules filled with active thermoset monomers, which are well-dispersed in a thermoplastic media. At the time of fixing the connection, and due to the applied mechanical force from the closure of the nut on the adhesive-coated screw, the microcapsule shells rupture and the reactive monomers release and flow into the gaps between the screw and the nut, and finally by chemical reactions, the connection between the screw and the nut is tightened. Therefore, this type of adhesive reveals appropriate storage time, with proper bonding strength between the joints, at the service life. In this article, we introduce and investigate the thread lockers adhesives containing microcapsules filled with reactive monomers.