Anhydridehärdare

Anhydridehärdare, also known as anhydride curatives, are a class of chemical compounds used to cure epoxy resins. They are typically cyclic anhydrides that react with the epoxy groups and hydroxyl groups present in the epoxy resin system. This reaction leads to the formation of a three-dimensional crosslinked network, transforming the liquid resin into a rigid, solid material. The curing process is generally carried out at elevated temperatures, although some anhydride curatives can be formulated for room temperature curing with the aid of accelerators.

The choice of anhydridehärdare significantly influences the properties of the cured epoxy resin. Different anhydrides offer varying degrees of reactivity, glass transition temperature (Tg), thermal stability, mechanical strength, and chemical resistance. Common examples include phthalic anhydride, maleic anhydride, hexahydrophthalic anhydride, and nadic methyl anhydride. The stoichiometry, meaning the precise ratio of anhydride to epoxy groups, is crucial for achieving optimal crosslinking and performance. Incorrect ratios can lead to undercured or overcured materials with compromised properties.

Anhydride-cured epoxy resins are widely used in various applications due to their excellent electrical insulation properties, good mechanical strength, and resistance to heat and chemicals. They are found in electrical potting and encapsulation, composite manufacturing (such as in aerospace and automotive industries), coatings, adhesives, and tooling. The low viscosity of many anhydride systems can also be advantageous for processing.