Polymers and resins
The resins are polymers that have synthetic origin. A polymer is characterized as a large molecule that is formed by combining smaller molecules. Resins can be further classified into thermosetting and thermoplastic. The thermoplastic resins can be molded once again when subjected to high temperatures and when they are allowed to cool, they become stiff. The thermosetting resins cannot be molded again after it has been cured.
Polyvinyl acetate, siliconeresins, polyamides and cyanoacrylate are all thermoplastic adhesives that are commonly used as industrial adhesives. These resins or polymers are oil resistant; however, they resist poorly to water, heat and creep when there is high loading. This type of industrial adhesive is capable of binding various materials like the laminates, wood, metal and ceramics. The resins are also widely used in the screw lock assemblies and in other applications.
Some of the usual types of thermosetting industrial adhesive are the polyurethranes, epoxy resins and phenolic resins. The epoxy resins like other thermosetting resins can also be hardened using heat, catalysts, hardeners or ultraviolet light. You need to be careful though since the hardening agent is dependent on the industrial requirement of the product. A structural adhesive that has high performance has very high heat resistance and chemical resistance especially those that are subjected to curing process at extremely high temperature.
The epoxy adhesives are a common product that is used in the automobile and aircraft industries. The polyurethrane resins are able to cure fast and can also bond with concrete surfaces. The phenolic resins on the other hand are used mainly in manufacturing plywood.
When the curing mechanism is set as the criteria, the adhesive can be classified into as follows: chemically hardening, physically hardening and pressure sensitive polymers. The different types of physically hardening adhesives are as follows: water-based adhesives, hot melt adhesives, organic solvent adhesives and the plastisols. This category of adhesives includes those that can be readily melted like the thermoplastics.
Hot melt adhesives are primarily used in packaging, electronic industries and in furniture binding. The solid adhesives tend to soften when heated. They then evenly wet the substrates that are made in contact with them and when cooled are solidified. In the vehicle industry the adhesive plastisol is commonly used. The water-based adhesives on the other hand are easy-to-clean adhesives and contain resins that are dispersed or dissolved in water. The two classes of polymers that are water-based are contact adhesives and wet bonding adhesives.