The addition of plasticizers and tougheners can increase the flexibility of the adhesive layer, improve the impact toughness of the adhesive layer, and improve the fluidity of the adhesive. However, too much amount will reduce the mechanical properties and heat resistance of the adhesive layer. Usually the amount is less than 20% of the sticky material.
Plasticizer is a high-boiling liquid or low-melting solid compound that is miscible with the sticky material, but does not participate in the curing reaction, such as dibutyl phthalate, triphenyl phosphate, and so on.
Toughening agents are involved in the curing reaction, and most of them are viscous liquids, such as low-molecular polyphthalein limbs, polysulfide rubber, and the like.
Taking polyvinyl chloride plasticization as an example, due to the polarity of the chlorine atoms on the molecular chain of polyvinyl chloride, the intermolecular force is strong, the processing temperature is high, and degradation is easy to occur. Plasticizer is added to polyvinyl chloride and heated. Plasticizer molecules can be inserted between the molecular chains of polyvinyl chloride. The polar part of the plasticizer interacts with the polar distribution of polyvinyl chloride. After cooling, the plasticizer molecules remain in the At the insertion position, the non-polar part of the plasticizer exerts an isolation function, weakening the intermolecular force of the polyvinyl chloride, so as to improve the plasticity and flexibility of the polyvinyl chloride, and reduce the processing temperature of the polyvinyl chloride.