Nylon Salt (AH Salt)
Nylon salt is produced by the aqueous reaction of adipic acid and HMDA. The product is available either as an aqueous solution (52-62% strength) or as a dry crystalline powder. Salt solution can be used as a starting material for nylon 66 polymer but the high concentration of water in the product results in corresponding logistics charges. 52% salt solution is thermally stable at ambient temperature, whereas 62% salt solution requires to be maintained above 90°C in order to prevent crystallisation.
Dry salt is more convenient to handle and has found application in several niche sectors, for example as an additive in nylon 6 film, a reactant in hot melt adhesives, or in conjunction with caprolactam in the production of nylon co- and ter-polymers, e.g. nylon 666. It can also be used as a starting material for nylon 66 polymer by dissolution in hot de-ionised water. This route is not commonly used however as the cost of first dehydrating the salt and then re-dissolving adds considerable cost.