Alzchem (Trostberg, Germany) is a manufacturer of specialty chemicals. Among its products is the Dyhard product line of latent curatives for epoxies that, when mixed with epoxy resin, yield compounds with long working life and the ability to cure quickly at elevated temperatures to form parts with optimal mechanical and thermal properties.

Alzchem’s flagship product line is the Dyhard 100 series dicyandiamide. Dicyandiamides are preferred for their long open time in a prepreg system to impregnate and wet out glass or carbon fiber fabrics. The high cross-link density of diyandiamide-cured systems yields final products with high T_g and high strength. Dyhard 100 products come in a variety of particle sizes, the most popular of which is Dyhard 100S with a d98 particle size less than 10 µm.

Alzchem also offers a broad range of urone and imidazole accelerators for this dicyandiamide series. Selection of the right accelerator package enables the formulator to compound an epoxy with the process and performance qualities required for specific aerospace or automotive applications; Dyhard accelerators are said to give the formulator different ways of balancing the reactivity of the epoxy compound with the open time that’s needed.

The Dyhard product line also includes Dyhard Fluids, a line of liquid latent epoxy curatives. These products are designed with filament winding applications in mind. The days-long pot life of impregnation baths formulated with Dyhard Fluids can reduce downtime, cleanouts and costs, when winding high-strength, high-T_g products. Dyhard Fluids have also found a home in prepreg applications where cosmetic appeal is a desirable attribute.

A new product now only available from Alzchem is the Dyhard LA1 latency additive. This class of products is reported to more than triple the pot life of an accelerated Dyhard 100/epoxy formulation. Alzchem says this can now be done without sacrificing the physical properties or the reactivity of the system. Fast-curing prepregs can now be manufactured without the need for refrigerated transport to the molder.