Лако-красочные материалы — производство

Since bases are catalysts for the curing reaction and acids are stabilizers for the cya­noacrylates, the pH value of the surface will control the cure speed. Surfaces that tend to be acidic will cure slowly compared to a neutral surface, which in turn will cure more slowly than an alkaline surface. In most applications the objective is to speed the cure; therefore, all the commercially available activators are weak bases dissolved in a volatile carrier. Applying an activator to a surface places a layer of the weak base in position to initiate the cure. Since they are stronger bases than moisture, they are able to neutralize the stabilizer systems in the adhesive more effectively, and thus they can tolerate larger gaps than would be possible with moisture alone. In general, the fixturing time is 10 times faster with activator than without it. Even with activator, the effect of the gap is clear (see Table 4).

Another advantage of the activator is the ability to cure a film or drop of the adhesive on a surface. The activator can be applied either to the surface being coated or to the top surface of the adhesive. The adhesive cures to a clear, hard, dry plastic that can be used to locate parts in position or to form a protective coating. Because the curing reaction is ionic, it is not sensitive to oxygen as are free-radical reactions, and it will cure through to the surface without the tackiness associated with free-radical curing systems.