Epoxy resin is a hard substance created when two substances, a epoxide and a polyamine, are combined. The epoxy is used in many different applications such as creating molds, strengthening fiberglass and in heat-resistant situations.
Structurally, it most cases consists of the two chemicals : long polymer chains of bisphenol A and epichlorohydrin molecules, and polyamine molecules that links these polymer chains into a net-like sheet From a manufacturing standpoint, the two tubes of liquid in a retail epoxy dispenser are filled with separate solutions of epichlorohydrin-bisphenol polymers and polyamine molecules. When mixed together, the hardening or “curing” that results is actually the multiple amine (-NH2) groups in the polyamines breaking open the epicholorhydrins’ trigular epoxy (C-C-O) groups to form a nitrogen-carbon bond.
To begin, producers add a strong sodium hydroxide (NaOH) solution to a tank containing bisphenol A solution. The basic hydroxide ions strip hydrogens from the bisphenol to create water. Meanwhile, the Na+ ions help stabilize the bisphenol’s negatively-charged oxygen atoms. Next, a concentrated epichlorohydrin solution (approximately 3 times that of the original bisphenol A solution), is added to the mixture. The charged oxygen atoms on the bisphenol A, knock the chlorine atoms away to bond with the epichlorohydrin molecules. The resulting chloride ions (Cl-) are then neutralized by the sodium ions (Na+) in solution.
When combined, they bond together attaching on a chemical level in a criss-crossed fashion that makes the resulting substance strong. This reaction takes some time to develop and is normally called the curing of the resin. Depending on how thin the two substances are poured, and the mix of hardeners and resins, the curing time can vary. In some cases, heat can be applied to speed the drying time up, but normally it is cured only by time. 2-Methylimidazole(C4H6N2, CAS No. 693-98-1) is used in epoxy resins as a curing agent.
Storage and Results
The chemicals are contained separately until needed so they do not react too soon. When packaged for resale, they are either placed in two separate bottles or one bottle with two compartments. These can generally be found in craft stores. The resulting hardened material is generally a clear substance that has a look like glass. In some cases, a person might have seen an example in a restaurant where items are placed on the tables and sealed with the resin. The customers can still see the items but cannot get to them because they are under the surface of the compound.