The Role Of Plasticizers And Tougheners in Adhesives
Jun 18, 2021
The addition of plasticizer and toughening agent 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 dosage will reduce the mechanical properties and heat resistance of the adhesive layer. Usually the addition amount is within 20% of the viscous material.
Plasticizer is a high boiling point liquid or low melting point solid compound, which is miscible with viscous materials, but does not participate in the curing reaction, such as dibutyl phthalate, triphenyl phosphate, etc.
Toughening agents participate in the curing reaction, and most of them are viscous liquids, such as low-molecular-weight polyphthalein, polysulfide rubber and so on.
Taking PVC plasticization as an example, due to the polarity of chlorine atoms on the molecular chain of PVC, the intermolecular force is very strong, the processing temperature is high, and it is prone to degradation. Add a plasticizer to the polyvinyl chloride and heat it. The plasticizer molecule can be inserted between the polyvinyl chloride molecular chains. The polar part of the plasticizer interacts with the polar distribution of the polyvinyl chloride. After cooling, the plasticizer molecules remain In the insertion position, the non-polar part of the plasticizer plays a role of isolation, weakens the force between the polyvinyl chloride molecules, and achieves the purpose of improving the plasticity and flexibility of the polyvinyl chloride and reducing the processing temperature of the polyvinyl chloride.
