Some of you may be familiar with the fact that most of epoxy based 2-component adhesives create an exothermic reaction as the two components are mixed together. The heat generated this way is proportional to the amount of adhesive being mixed. This may be problematic for three main reasons.
First, the temperatures developed in such a reaction are more than high enough to cause serious burn injuries to the operator if all safety procedures are not carefully observed.
Second, increased heat accelerates the reaction leading to a premature cure and decreased working time or a so called: runaway reaction.
Third, the generated heat can cause damage to bonded parts.
One way around this is to mix smaller quantities of adhesive little by little as they are being used. This, however, can complicate and prolong the entire manufacturing or repair process, so it’s not always the best option. Additionally, mixing less product at a time doesn’t really help in case of risk to damaging the parts.
This doesn’t have to mean that bonding is still not an option. There is now a line of so called Loctite universal bonders – patented hybrid technology. When it comes to structural bonding, they are a valid and in many cases, better alternative to epoxies.
Loctite HY 4070 hardly develops any heat at all during mixing because it does not contain an epoxy component but is a hybrid of cyanoacrylate and acrylic.
Loctite HY 4090 on the other hand, even though it has an epoxy component, due to the cyanoacrylate component in the material, is self-limiting the temperature developed during mixing and poses none of the above mentioned risks.
In addition to that, while epoxies are quite limited to only certain types of substrates, with the universal bonders you can bond a number of completely different materials with very different properties. They fixture between 2 and 6 minutes, develop high strength bonds and withstand the temperatures up to between 120 0C and 150 0C once cured.
They are also much safer to handle than epoxies, which is an increasingly important fact for the conscientious employers.
More on universal bonders can be found on our website.