Epoxies are some of the most versatile materials for just about any use. Since their introduction in the 1940s, they have found their way into thousands of applications - all thanks to their high mechanical strength, heat, and water resistance, relatively quick curing times, low shrinkage rates, and outstanding adhesion. They're ideal for use as a protective coating or filler in various products, from concrete floor sealers to electrical component adhesives.
What Is Epoxy?
This material is a thermoset polymer used to make a range of protective coatings, fillers, and adhesives. It's viscous as a liquid but cures and solidifies quickly when mixed with hardeners and additives. Curing times and pot life can be modified for the specific application and will depend on the hardeners and additives used.
Once hardened, it displays high strength, dimensional stability, and chemical resistance. The epoxy resin on the market also sticks easily to different materials, including wood, concrete, stone, glass, and metal.
First, let's get the minor niggles out of the way. Unmodified epoxy is rigid and brittle, has low impact and peel strength, and requires careful mixing. It also needs time to cure at a set temperature.
While it does stick to the most commonly used materials, it won't adhere to wax, polyethylene plastics, silicone, masking tape, or greasy surfaces. Lastly, the material can be irritant (but non-toxic), so wear protective gear, like nitrile gloves, goggles, and disposable respirators when applying.
The Many Advantages When Compared to Other Adhesives and Coatings
The long list of favourable properties is achieved with the addition of various curing agents, modifiers, and additives, lending epoxy resin different properties required for the application. The material has very low shrinkage once cured, a low level of creep under sustained loads, high mechanical strength and stiffness, good heat, and chemical resistance, and good permeability, making it ideal as a filler. It is also moisture-resistant, unlike polyester resin. Curing times can also be modified to suit.
Addtivies like rubber can provide flexibility and resistance to fatigue and cracking, thermoplastics, glass, and graphite add strength, flame retardants reduce flammability, powder metals where conductivity is important, and dyes and colours when you want a specific result.
Compared to vinyl and polyester resins, epoxy resin has much better adhesion, is stronger and harder, has a higher resistance to cracking, doesn't suffer from water ingress, and won't degrade when exposed to liquids.
As an Adhesive
This material is frequently used in adhesive applications. Epoxies make up the majority of structural or engineering adhesives, in part because of their strong bonding power, heat resistance, dimensional stability, and adaptability to various substrates.
The substance is also used to make laminated wood for walls, roofs, and decks, as well as parts for automobiles and aeroplanes, a variety of sporting goods (bikes, golf clubs, snowboards, and kayaks), and pretty much any other product that needs to remain strong and waterproof under heavy use.
In Industrial Tools, Electronics, and Electrical Systems
Resins allow for strong binding. So, their uses can cut costs and production times during the manufacture of tooling equipment such as moulds, dies, laminates, and fixtures.
Additionally, the material is widely found in the electronics industry, where it is used in the production of insulators (due to low conductivity), as well as generators, motors, transformers, and even circuit boards with their high resistance to heat, dust, and moisture.
In Paints, Coatings, and Sealant
Many white goods, such as ovens, dryers, fridges and washing machines, contain epoxy paint or powder coatings due to their resistance to corrosion and general wear and tear. The coatings protect the appliances by reducing damage from abrasion and impact.
Epoxies are also used as protective and insulating coatings in ships, aircraft, and satellites, as well as in the energy sector in the production and coating of wind turbines and parts for hydroelectric power stations. The anti-corrosive properties make epoxy present in everyday household items, such as paint cans, canned food and metal containers.
The resins can additionally help to provide durable and high-gloss coating in outdoor flooring applications and act as sealers for concrete floors and other coatings used in industrial settings. One area where the material is extremely popular is indoor decorative flooring. This includes terrazzo, chip, and aggregate coatings in different colours and patterns and is often mixed with additives like paint chips for a unique look or polymer grit for a non-slip surface. A similar use is in decorative kitchen countertops.
Due to the strong adhesion, epoxies are particularly versatile in general repairs of household items. And since the material sticks to different surfaces and cures within minutes, it can be utilised in repairing glass, wood, ceramics, tiles, concrete, and metals with ease. For instance, crack injection concrete epoxy is commonly used to repair cracks and gaps in concrete floors and driveways.
The Different Types
There are dozens of types of epoxies, but most fall within two categories - casting and coating. While both display similar properties, it's important to select the right type for the intended purpose.
Casting, also called deep-pour epoxy, has low viscosity and longer curing times. It is mixed in a 2:1 ratio of liquid resin and hardener. it is ideally used for fully embedding objects in the resin, but is also useful in filling gaps and holes in various materials and increasing their strength and stability. Jewellery, electrical insulation and plastic moulds are just a few items that make use of the casting type.
Coating resin comes in a 1:1 ratio of epoxy and hardener. it cures more quickly and settles into a strong, durable, and water and chemical-resistant protective coat. Compared to casting, coating varieties are typically much tougher and harder, quite thicker, but applied in thinner layers. This is what's commonly used for flooring and sealing purposes, in addition to specialty applications like circuit boards.
Choosing the Right Option for Your Needs
When choosing epoxy for your project, there are several crucial factors to consider. You'll need to take into account the needed depth and thickness of the epoxy resin, the curing time, the viscosity (high vs low), and the durability of the finished product. In addition, consider how the mixture will be applied, and whether there's the need for any special properties, like self-levelling and bubble-release formulas, or resistance to yellowing (due to UV exposure and temperature variations) in determining the final outcome.
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