Epoxy, or polyepoxide, serves as a thermosetting polymer that initiates polymerization (also known as curing) when mixed with a hardener. The polymer itself is gleaned from a chemical reaction—usually between epichlorohydrin and bisphenol-A—which results in an epoxy resin. Epoxy can be modified to serve a multitude of purposes, but is most commonly found in paints, coatings, and adhesives.
Epoxy: Paint, Coatings, and Adhesives
One of the most standard epoxy coatings is a two-part waterborne coating—it is UV resistant, extremely hard, and resists abrasion. As a result of these properties and because of its excellent adhesion, it is commonly used to coat metal and other components that must withstand a fair amount of wear-and-tear. Additionally, waterborne epoxy coatings are less toxic than solvent-based epoxies, meaning they’re easier and safer to work with and dispose of. Industrial and automotive demands are high for waterborne epoxy because the coating is quite heat resistant, which reduces the chances of eventual peeling as a result of burning or heat intolerance. As with most epoxy, waterborne epoxy coatings harden and dry quickly once mixed with the appropriate hardener, so timely application is essential.
Polyester epoxy includes powder coatings, which are a common choice in coating white metal, such as refrigerators. Fusion bonded epoxy powder coatings can be used to line potable water pipelines, and are also used to reinforce concrete and prevent corrosion in standard steel pipes. Epoxy can also serve as a primer in applications that are prone to rust and corrosion, as it helps other coatings adhere.
As an adhesive, epoxy is widely used in the construction of automobiles, boats, bicycles, airplanes, and numerous other components that are routinely expected to maintain high levels of performance while exposed to the elements. Epoxy is often cured using heat—epoxies cured using heat tend to exhibit higher heat and corrosion resistance than those cured at room temperature—a cured epoxy demonstrates higher heat resistance, up to 350 degrees Fahrenheit, than most other common adhesives. They can be manipulated to be fast or slow setting, clear or opaque, malleable or rigid. They also work well as adhesives on solid wood furniture, stone, and glass, and can easily by altered to suit and array of applications.
Epoxy use isn’t limited to adhesive and coating applications, but serves a wider range of industries—epoxy can be found in industrial tooling, electrical systems, and in marine and aerospace fields.
In industrial tooling applications, epoxy is used to manufacture molds, models, castings, and fixtures to replace traditional metal and wood versions of the same. Epoxy can also be used to replace polyester resins and vinyl resins in fiber-reinforced parts and though they are somewhat more expensive the parts tend to be strong and temperature-resistant.
Because epoxy resins are good insulators, they are commonly used in integrated circuits, transistors, and hybrid circuits to protect the electrical components from external dirt, dust, and moisture. In large circuit board applications, epoxy is used to bind together various components and even comprise part of the soldering mask.
Epoxy can serve as a nice clear coating, but with additives can easily be transformed to resemble treated granite and a variety of other looks—this cuts down on the cost of materials like stone, while providing the treated surface with the benefits and strength of a traditional epoxy coating.