Classifications of Industrial Adhesives and Their Applications

There are numerous types of adhesive substances specifically designed for industrial purposes. In general terms, an adhesive is a type of substance that binds or holds two separate surfaces together. Industrial adhesives are typically classified on the basis of their composition, cure mechanism, and adhesive properties. Cure mechanism is the process by which an adhesive hardens. This could be through the use of chemicals, ultraviolet light, heat, or other processes. The way that adhesive materials are used in industrial settings depend on their physical and chemical properties:

• Resins – Resins are synthetic polymers (a polymer is a large molecule made up of a combination of smaller molecules or particles). They can be classified into two types, including thermoplastic and thermosetting resins. Thermoplastic resins can be remoulded at high temperatures and become rigid when cooled. Thermosetting resins on the other hand, cannot be remoulded after they have already cured.

• Thermoplastic adhesives – PVA or polyvinyl acetate is a common example of a thermoplastic adhesive. Other types that are traditionally used for industrial purposes include cyanoacrylate (superglue), polyamides, and silicone resins. These adhesives are oil-resistant but they exhibit poor resistance to water and heat. They also tend to creep under high loading. Thermoplastic adhesives can bind most types of materials, ranging from wood to metal, ceramic, and even laminates. Other common applications include screw lock assemblies and surface binding.

• Thermosetting adhesives – Common types of thermosetting industrial adhesives include epoxy resins, phenolic resins, and polyurethanes. Similar to thermosetting resins, they can be hardened with the use of catalysts or hardening agents, as well as heat or ultraviolet light. High-performance structural adhesives often have high heat and chemical resistance, particularly ones that are cured using extremely high temperatures.

On the basis of curing mechanism, industrial adhesives can be further classified into pressure sensitive, physically hardening, and chemically hardening resins. Common types of physically hardening adhesives include plastisols, hot-melt adhesives, organic adhesives, and water-based adhesives. This category also includes other types of adhesives that can be melted like thermoplastics. They are primarily used in packaging, furniture, and electronics industries. Most physically hardening adhesives soften upon heating and they wet substrates that come in contact with them, but solidify when cooling. Other physically hardening industrial adhesives like plastisol are widely used in the automotive industry.

Chemically hardening industrial adhesives require some sort of chemical reaction to facilitate bonding. They can be classified into single and two-component adhesives. They also differ in their curing process, including resins that harden through heat, moisture, or radiation cure. Others are anaerobic, while others like urethane, epoxies, and silicone adhesives require a two-component design to facilitate adhesion. These adhesives are commonly used in the automotive, microelectronics, optics, and medical industries.

Finally, pressure-sensitive resins are those that bond surfaces using sufficient pressure. They are mainly employed in filter frames and membrane switch assemblies, as well as those that require temporary/easily-removable bonding.

About the Author:

Jimmy Walsh, who is also associated with CT1 Ltd, writes this article. They are specialised in designing, development, and distribution of high quality and exclusive problem preventing products for the construction and building repair market.

For more information visit: CT1 Ltd