Cyclic acid anhydrides are widely employed as curing fixers for epoxy resins. Compared with amines they are less skin sensitive and generally give lower exotherms in curing reaction.
Some acid curing agents provide cured resins with very high heat-distortion temperatures and with generally good mechanical and even electrical, and chemical properties.
· The acid-cured resins, however, show less chemical resistance than
amine-cured resins because of the susceptibility of ester groups to hydrolysis.
Anhydride curing agents find use in most of the important applications of epoxy resins, particularly in casting (etc).
- The acid anhydrides are preferred to acids since the latter are generally less soluble in the resin and also release more water on cure, leading to foaming of the product.
