Toughening agent

Some thermosetting resin adhesives, such as epoxy resin, phenolic resin and unsaturated polyester resin adhesive, have low elongation and high brittleness after curing. When the bonding part is subjected to external force, it is easy to crack and expand rapidly. , resulting in cracking of the adhesive layer, fatigue resistance, and cannot be used for structural bonding. Therefore, it is necessary to try to reduce the brittleness, increase the toughness, and improve the bearing strength. Any substance that can reduce brittleness and increase toughness without affecting other main properties of the adhesive is a toughening agent. It can be divided into rubber toughening agent and thermoplastic elastomer toughening agent.