How does potlife affect additive selection for waterborne 2K epoxy coatings?
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||Jim Reader |
Lead Research Chemist
The potlife of a 2K waterborne coating is an important parameter for formulators and applicators, because the for-mulation components begin re-acting when mixed and continue reacting through the potlife until the polymer formation reaches a critical point where one or more of its application properties (including minimum film formation temperature) are no longer suitable to apply or form a suitable coating. However, recent tests have shown that the surface tension of 2K waterborne epoxy coatings does not vary much through the duration of its potlife; therefore, efficient, low-foam wetting agents, such as Surfynol® 420 surfactant, can maintain excellent surface appearance and wetting properties during this time. Other wetting agents, like silicones, can show orange peel, especially early after mixing. Surfactants, such as the alkyl-phenol-ethoxylate-free Carbowet® 109 surfactant, can also help to ensure that hydrophobic liquid epoxy resin is quickly emulsified by the waterborne curing agent, preventing craters and inconsistent film formation if the coating is applied too soon after mixing.