Epoxy resins are a type of thermosetting polymers with unique mechanical and strength properties. They are created by mixing BPA and epichlorohydrin (ECH), which are then reacted to create the basic monomer unit of the epoxy resin called BADGE or DGEBA. The properties of cured epoxy resins are determined by a chemical process called curing or hardening. Epoxy is the family of basic components or cured end products of epoxy resins, also known as polyepoxides.
The epoxide functional group is also collectively referred to as epoxy. Various substances can be used as hardeners, including polyamines, aminoamides or phenolic compounds. Epoxy resins are formed from a long chain molecular structure similar to vinyl ester with reactive sites at each end. However, in epoxy resin, epoxy groups instead of ester groups form these reactive sites.
The absence of ester groups means that the epoxy resin has a particularly good water resistance. The epoxy molecule also contains two groups of rings in its center that are better able to absorb mechanical and thermal stresses than linear groups and therefore give the epoxy resin very good stiffness, toughness and heat resistance properties. Aromatic amines were widely used as hardeners of epoxy resin, due to the excellent final properties when mixed with a mother resin. One of the best examples was a system of using solvent-free epoxies to bait ships during construction, this used a spray system without hot air with premix on the head.
The epoxy resin market is dominated by the Asia-Pacific region, which contributes 55.2% of the total market share. Epoxy resin is the main type of structural adhesive and engineering adhesive used in human life applications, and has a high performance bond strength. Low molar mass (mono-, bi- or polyfunctional) aliphatic glycidyl epoxy resins are formed by the reaction of epichlorohydrin with aliphatic alcohols or polyols (glycidyl ethers are formed) or with aliphatic carboxylic acids (glycidyl esters are formed). The resin structure can be designed to produce a number of different products with varying levels of performance.
Epoxies are more expensive than polyester resins and vinyl ester resins, but generally produce stronger and more temperature-resistant thermosetting polymer matrix composite parts. They are used to bond copper foil to circuit board substrates and are a component of the solder mask on many circuit boards. However, it is very useful if a protective layer is applied to a small and delicate object, since polyester resins are less likely to yellow over time than epoxy coatings. The chemistry of epoxies and the range of commercially available variations allow curing polymers to be produced with a very wide range of properties.
Knowing how epoxy resin is manufactured is essential for understanding its properties and applications in various industries. This comprehensive guide provides an overview of how epoxy resin is manufactured and how it differs from polyester resin.