Syrehämmning

Syrehämmning, also known as oxygen inhibition or oxygen inhibition layer, is a phenomenon observed during the curing of certain types of polymers, most notably UV-curable resins and some two-part epoxies. It occurs when oxygen in the atmosphere comes into contact with the surface of the liquid resin during the curing process. Oxygen interferes with the polymerization reaction, preventing the free radicals or other reactive species from fully crosslinking at the surface. This results in a tacky, uncured, or partially cured layer on the surface of the otherwise solidified material.

The extent of syrehämmning varies depending on the specific chemistry of the resin system. Some formulations are highly susceptible, while others have been designed to minimize this effect. The tacky layer is often undesirable as it can attract dust and debris, and it may compromise the adhesion of subsequent layers or coatings.

To mitigate syrehämmning, several methods can be employed. One common approach is to cure the resin in an oxygen-deficient environment, such as under nitrogen or argon. Another method involves using a higher intensity of UV light or a longer exposure time, which can sometimes overcome the inhibitory effect of oxygen. Alternatively, a thin barrier layer, like a plastic film or a sacrificial coating, can be applied over the resin surface during curing to prevent oxygen contact. Some UV-curable formulations also incorporate specific additives that reduce their sensitivity to oxygen. In the case of two-part epoxies, proper mixing ratios and curing temperatures are crucial to ensure complete polymerization and minimize surface tackiness.