Structural adhesives must be chosen according to processing requirements and application’s performance. Once these are determined, next thing to do is to choose the type of adhesive that effectively and economically meets those needs. Structural adhesives are classified by their chemistries: acrylics, epoxies, urethanes, and cyanoacrylates or commonly known as instant adhesives. Each of these types can be tailored fit to some extent, such as adding diluents, thickeners, and toughening agents. While they differ from each other, they can be compared based on their general chemical properties. But still, users and engineers alike have to review the properties of the adhesives of interest.
For this purpose, let’s take a closer look at instant adhesives or cyanoacrylates. They offer good shear strength on rubber and plastic substrates. However, they are poor in terms of resisting peel and impact and may require primers. Cyanoacrylates are usually chosen for convenience because they don’t need mixing and have a longer pot lives. However, once they have bonded the parts together, they can’t be repositioned. This earns them the name instant adhesives, which also means high risk of accidental skin bonding. They also have the tendency of blooming or the formation of unsightly whitish or rainbow haze around the joint line. But there are some types that can minimise blooming.
As the general rule in using instant adhesives or other adhesive in this matter, when applying the adhesive outdoors during a hot summer, the open time can be as lower as half of what is indicated on the datasheet. While application during a cool fall or spring day with low temperatures, open time might be twice as reported. In other words, more care is needed to finish bonding or curing quickly during hot days or added time during cold days. If you want to learn more about instant adhesives for your specific application, contact Invertech Canada today!