Most common epoxy resins are produced from a reaction between epichlorohydrin (ECH) and bisphenol-A (BPA), though the latter may be replaced by other raw materials (such as aliphatic glycols, phenol and o-cresol novolacs) to produce specialty resins.
The epoxy resins can be obtained in either liquid or solid states. The two processes are similar. Firstly ECH and BPA are charged into a reactor. A solution of 20-40% caustic soda is added to the reaction vessel as the solution is brought to the boiling point. After the evaporation of unreacted ECH, the two phases are separated by adding an inert solvent such as methylisobutylketone (MIBK). The resin is then washed with water and the solvent is removed by vacuum distillation.The producers will add the specific additivesto create a formula that lend special properties such as flexibility, viscosity, color, adhesiveness, and fastercuring, depending on a particular application.
In order to convert epoxy resins into a hard, infusible, and rigid material, it is necessary to cure the resin with hardener. Epoxy resins can cure at practically any temperature from 5-150oC depending on the choice of curing agent. Primary and secondary amines are widely used to cure epoxy resins.
Posted in: FAQ - Epoxidharz
