These are adhesives which, forming a joint, are able to support a functional load which is equal at least to that of the substrates bonded between them. They can replace the mechanical fixings fulfilled through a nut/bolt system, rivets or weldings. The joint realized with the structural adhesives may have a higher performances than the mechanical one. Within this range we find one-part or two-part adhesive products.
Some one-part adhesives are moisture curing (they crosslink with air humidity), others have to be heat-activated. The range of structural one-part adhesives includes epoxy, cyanoacrylate and polyurethane products. For these last ones, which are solvent-free, there are specific devices for rapid industrial applications with different working times, according to the chosen adhesive.
TWO PARTS ADHESIVES
Two-parts structural adhesives dry through a chemical polymerization at room temperature, achieved by an established proportion mixing of two parts that, during the conservation phase, are kept separated. The formulation of both parts and their mixing proportions allow a wide choice as for the working times of the two-parts adhesives. Thanks to these characteristics, you can have adhesives with very long or very short “open times” and with a more or less rapid curing time. Two-parts components include products suitable for bondings where it is necessary that the adhesive remains immediately in position and doesn’t sag - although remaining workable to favour the replacement of the joint – for instance when it is applied in assembly operations which occur bottom up. Structural joints may request capacities of:
Therefore there are rigid formulated adhesives, flexible ones, the so-called toughened ones which add up strength and flexibility quality.