Epoxy resins are reactive polymers and prepolymers that contain epoxide groups. Epoxies react with themselves after catalysts or co-reactants like phenols and amines are added. Compared to other types of resins, cured epoxies have superior mechanical properties and chemical and thermal resistance. Their versatility means they are effective in varied applications, such as adhering structural components, electrical insulation, and coating concrete. Depending on the type of epoxy, it can be used on a variety of materials, including wood, metal, plastic, and stone.
Here is an overview of the different types of epoxy resins, their properties, the curing process, and their applications.
Key Properties of Epoxy Resins
These are the main properties of epoxy resins:
- High strength
- Minimal shrinkage
- Superior adherence to a variety of substrates
- Electrically insulating
- Chemical and solvent resistance
- Low toxicity
- Low cost
Epoxies cure quickly and are suitable for a wide range of substrates, especially composite applications.
What Are the Different Types of Epoxy Resins?
Epoxy resins can be categorized by the chemical chain the reactive epoxy group is bonded to. Here are the most common epoxy resin types:
- Aliphatic Epoxy Resins: These epoxy resins are created through double bond epoxidation or through a reaction with epichlorohydrin.
- Cycloaliphatic Epoxy Resins: This epoxy has one or more aliphatic rings in the epoxy ring molecule. They have a distinct aliphatic structure, a high amount of oxirane, and no chlorine. This chemical structure results in low viscosity, low dielectric constants, strong weather resistance, and a high glass transition temperature (Tg).
- Bisphenol Epoxy Resins: Bisphenol-A diglycidyl ether (DGEBA) is a popular resin for commercial applications. It is formed from the reaction of bisphenol-A and epichlorohydrin.
- Novolac Epoxy Resins: These resins are created with improved functionality to strengthen the cross-link density of the cured system, making them ideal for high-temperature applications that require extreme chemical resistance. Novolac epoxies do not contain volatile organic compounds (VOCs) or solvents.
- Glycidylamine Epoxy Resins: With a high level of functionality, these epoxies are generated from the reaction between epichlorohydrin and aromatic amines. Triglycidyl-p-aminophenol and N, N, N’, N’-tetraglycidyl-bis-(4-aminophenyl)-methane are industrial grades that have low to medium viscosity at room temperature, so they are easier to process.
- Epoxy Resin Diluents: Epoxy diluents are made from aliphatic alcohols or polyols. These materials can be monofunctional, difunctional, or greater functionality.
Curing Time and Process for Epoxy Resins
When the epoxy resin is mixed with a hardener, a chemical process converts the liquid material into a solid. This is known as the cure period—the epoxy mixture transitions from a liquid to a gel to a solid. The epoxy’s temperature is the main influence on curing time, and the warmer the epoxy, the faster the cure. Three factors influence the epoxy’s temperature: ambient temperature, the temperature of the surface where the epoxy is applied, and the heat created by the epoxy as it cures (exothermic heat).
In warmer temperatures, a slow hardener is added to increase open time. Technicians can also make small batches and pour the epoxy into containers with larger surface areas to dissipate the exothermic heat. In colder temperatures, a faster hardener or additional heat can raise the epoxy’s temperature to facilitate curing. Applied before mixing or after application, supplemental heat sources include a heat lamp or hot air gun.
Epoxy Resin Uses and Application Methods
Epoxy resin has a wide range of applications, including coatings, adhesives, and producing composite materials, including those with carbon fiber and fiberglass reinforcements. The properties of an epoxy can be altered to suit various needs, such as electrical conductivity.
Among the most popular uses for epoxy resin is as an adhesive for structural and engineering applications. Epoxy adhesives can effectively attach products as varied as aircraft components, golf clubs, and snowboards.
Epoxy resins can be used to create tools such as molds, castings, master models, laminates, and fixtures. Epoxy plastic tooling is an excellent substitute for wood or metal materials. In most industrial processes, epoxy tooling increases efficiency and reduces cost and lead times.
Epoxy resins are crucial in the electronics sector, where they are used to make insulators, motors, transformers, and generators. Epoxies are valued for their excellent electrical insulation and ability to provide protection in harsh environments.
Its adhesive properties make epoxy suitable for consumer use, such as repairing broken ceramic, wood, latex, and metal objects. Consumers also use epoxies for artistic or DIY projects.
Epoxy Resin Products From Copps Industries
The types and properties of epoxy resins mean they are widely used across industries for various adhesive and insulating applications. For more than 40 years, Copps Industries has been a major supplier of high-quality epoxy resin solutions to the mining, electrical, civil engineering, and adhesives industries. Our epoxies are tested extensively for quality assurance. Specific solutions include composite epoxy systems, concrete joint fillers and coatings, wear-resistant maintenance products, and more. Our line of over 500 products serves more than 400 customers in 27 countries.
Request a quote to learn more about epoxy resins or our products and capabilities.