Epoxy adhesives are extensively used for bonding two substrates in Industrial applications. Epoxy adhesives are used for bonding, sealing, coating, encapsulation, etc. They are the best choice for industrial use due to their unique mechanical, chemical, thermal and electrical properties.
Epoxies offer excellent adhesion and are highly flexible, lightweight and customisable. Manufacturers can tailor the epoxy’s curing time, mechanical strength, chemical properties, electrical and thermal conductivity, electrical and thermal resistance, etc., creating different types of epoxy formulation. Different types of epoxies are used for unique applications throughout different industries.
Want to learn more about the types of epoxy adhesives? Continue reading this blog for an overview of epoxy variations and uses!
A] Types Of Epoxy Adhesives Based On Components
1. One Component Epoxy
As the name suggests, one-component epoxy systems are adhesive with the epoxy resin and curing agent present in a single mixture. The curing agents present in the epoxy mixture are inactive and only active after the right curing conditions are introduced.
The right curing condition is usually heating the epoxy for a particular time period. Specially formulated epoxies are also available that cure in lower temperatures. Because one-component epoxies do not have a second element, there is no hassle for mixing. It also eliminates the chance of error in the mixing ratio and reduces wastage. One-component epoxies are suitable for a wide range of industries, including aerospace, electronics and OEM.
1. Two Component Epoxy
Two-component epoxies are adhesives where the epoxy resin and hardener are stored separately. Before applying the epoxy, the resin and the hardener must be mixed in a specific ratio, either by weight or volume, to get excellent bonding strength. It is crucial to follow the instructions the adhesive manufacturer provides to get the best results.
One of the best features of two-component epoxy over single-component counterparts is that they can be modified to suit the desired application. Chemicals, filaments, and pigments can be added to the mixture to modify the bonding strength, mechanical properties, chemical resistance, viscosity and flexibility, thermal and electrical properties, etc. This makes two-component epoxies very versatile. These types of epoxy are used in almost every industry for coating, potting, encapsulation, bonding and sealing applications.
B] Differentiating Epoxy Types Based On Properties
1. Heat Curing Epoxy
Every epoxy requires some form of curing mechanism to adhere to the entire surface and form strong bonds. Heat-curing epoxies require high temperatures to form strong bonds between substrates. Heat-curing epoxies usually are two-component epoxies; however, single-component heat-curing epoxies are also available. These epoxies are able to form strong bonds with dissimilar surfaces.
Because these types of epoxies require high temperatures to cure and set, they have impressive thermal resistance properties. Heat-curing epoxies can provide strong bonds even in higher temperatures, which many adhesives cannot withstand. The USP of heat-curing epoxy is that it provides unlimited working time at room temperature and begins curing only when exposed to higher temperatures. They are suitable for equipment which are constantly under extremely high temperatures.
2. Conductive Epoxy
Conductive epoxies are used for electronic component coating and encapsulation to protect circuits and PCBs from contamination. The conductive nature of the epoxy allows the free flow of electricity and heat in the electronic components to keep the system running without interruption. Electrical conductive epoxies can also be used as a viable alternative to soldering.
In addition to the electronic industry, these epoxies are used for electrical components in aerospace, automotive, and OEM industries. Thermal conductive properties of the epoxies help to dissipate heat and encapsulate heat sensors.
3. Extreme Temperature Resistant Epoxy
Many industrial epoxies have to withstand harsh and dynamic temperatures. Extremely high or low temperatures can damage the epoxy’s structural integrity and cause bonding malfunctions. The adhesive might melt if the temperature goes significantly higher than the epoxy can withstand. If the temperature exceeds the epoxy’s limit, the epoxy will crack. In both cases, the bonding strength and serviceability of the epoxy is compromised.
Extreme temperature-resistant epoxies are capable of withstanding temperatures over 300 degrees Celsius and cryogenic cold temperatures. These adhesives are the perfect solution for the aerospace, automotive, electrical, medical, oil and chemical industries.
4. Optically Clear & Non-Yellowing Epoxy
Optically clear and non-yellowing epoxies are used for optical lenses, fibre-optic, electro-optical, LEDs, touchscreen panels, LCDs, etc. These adhesives play a crucial role in the electronics, automotive, aerospace, and optical industries. These adhesives provide complete transparency, essential for such applications, without compromising bonding strength.
These adhesives can be modified to have excellent thermal and electrical conductivity or resistance, depending on the requirement. Additionally, you can expect dimensional stability, chemical resistance, abrasion resistance, and extreme temperature resistance from these epoxies. Optically clear & non-yellowing epoxies are also available in a range of reflective indexes for desired spectral transmission.
5. Chemical Resistant Epoxy
Industrial chemicals can degrade adhesives, corrode the equipment, and pose safety issues. Chemical-resistant epoxies are specifically designed for industries where they have to endure prolonged exposure to vigorous epoxies. These epoxies are widely used in the electrical and electronics, medical, and oil and chemical industries and processing plants.
These epoxies offer excellent resistance to acids, bases, gasoline, solvents, and alcohol. Chemical-resistant epoxies can also withstand the sterilisation process, so you can conduct thorough cleaning without worrying about damaging the bond. These adhesives have increased longevity as they are not affected by the weathering process as much as any other adhesives.
6. Low Out-Gassing Epoxy Adhesives
Out-gassing is a common problem in the aerospace industry; hence, low out-gassing epoxies are specifically designed for aerospace applications. However, low out-gassing adhesives also see extensive use in electronics, oil and gas, medical, optical and food industries. Adhesives have a tendency to release gases trapped in their chemical compositions under high temperatures or low pressure. These gases can contaminate the neighbouring equipment, such as lenses and sensors, causing inconveniences and safety issues.
Low out-gassing epoxies also have the electrical, thermal, and chemical properties required for industrial use. A high-quality, low-out-gassing epoxy must be able to withstand even the extreme temperatures and vacuum of space.
Conclusion
As we have discussed, adhesives can be tailored to accommodate different industrial requirements. Industries like aerospace, electrical, manufacturing, automotive, food and beverage, optical and medical can increase productivity and ensure safety by using epoxy adhesives that are tailored to their specifications.
It is crucial to understand the requirements of your industry to select the epoxy with the desired properties. Exploring epoxy variations is just as important for finding the one that suits your industrial needs. If you cannot find an adhesive that meets your specifications, you can always get a tailored epoxy. If you are looking for bespoke epoxy adhesives for industrial applications, contact Kohesi Bond today!
