Epoxy is a class of thermosetting resin derived by the polymerization of epoxides. It is capable of forming tightly linked cross-polymer structures, and can be either made into an adhesive or cured to form high-strength polymers.
Its areas of application range from Construction to Aerospace.
Manufacturing Process
Epoxy resins can be formed in either liquid or solid states by similar processes.
- Most common epoxy resins are produced from a reaction between epichlorohydrin (ECH) and bisphenol-A (BPA),
Bisphenol-A can be replaced by other raw materials, such as aliphatic glycols, phenol and o-cresol novolacs, to produce specialty resins.
- ECH and BPA charges are infused into a reactor.
- A solution of 20%-40% caustic soda, at its boiling point, is added to the reactor.
- The un-reacted ECH evaporates. The two phases are then separated by adding an inert solvent such as methyl isobutyl ketone (MIBK).
- The resin is then washed with water and the solvent is removed by vacuum distillation.
- Depending on the application demanded, specific compounds are added to lend required properties such as flexibility, viscosity, color, adhesiveness, or hardness.
- To produce hard, infusible, and rigid epoxy materials, the resin is cured with a hardener such as (primary and secondary) amines. Epoxy resins can cure at temperatures between 5oC and 150oC, depending on the curing agent being used.
Applications
The plethora of applications of epoxy resins include, but is not limited to,
- Making protective coatings, structural composites, electrical laminates, casting and encapsulation, regular adhesives, adhesives for aircraft honeycomb structures and paint brush bristles.
- As concrete topping compounds, body solders, laminating resins for airframe and missile applications, and for filament-wound structures and tooling fixtures.
- In marine finishes, structure steel coatings and tank coatings, aircraft finishes, automotive primers, and collapsible tube coatings.
- For concrete floor paints, gym and floor varnishes, spar varnishes, etc.
- As chemically resistant mortars and floor topping compound; in printing inks, in fabric treating applications in dental, surgical and prosthetics, for breaking petroleum emulsions, and for light weight chemically resistant foams.
- As additives for a variety of other plastic materials, such as vinyl and acrylic resins and natural and synthetic rubbers.
Conclusion
Like most other materials that are used widely, epoxy resins, too, have several benefits and drawbacks.
The plus sides are: growing demand and the introduction of newer grades leading to expansion of application areas. Whereas, the drawbacks are: the current small capacity plants, and lack of global competitiveness.
