It refers to a substance added so as to be equipped with properties as a product such as improvement of processability by granting plasticity (property where deformation is made easy by heating or force) to polymer materials such as synthetic resin, etc.

Plasticizer enters between polymer molecules to prevent strong bonding among polymer molecules. Because of this, empty spaces are produced, giving flexibility and elasticity to rubber or plastics to facilitate forming and change physical properties thereby assisting excellent properties to be had. It is also used for the purpose of reinforcing flexibility, cold resistance, volatilization resistance, electrical characteristics, etc. Plasticity may be displayed in some synthetic resins only when a plasticizer is employed.

Plasticizers enhance processability of plastics so as to allow use of plastics for places not allowing use in the past. Also, when a plasticizer is added, other properties of the product such as heat resistance, cold resistance, flame resistance, electrical properties, etc. can be improved. Ester bonding among plasticizers is relatively stable against heat, and has an advantage of allowing production of about long oligomers.