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Dycure 500-21


Dycure U500-21 represents a bi-functional, micronized accelerator based on a substituted urea. Being a highly active as well as a latent accelerator, its prominent use is preferably in combination with the highly latent curing agents of the Dycure® Dicyandiamide in thermosetting epoxy resin formulations.


As Dycure U500-21 does not contain halogens it may be preferred for applications where halogen-free formulations are required. In addition, Dycure® U500-21 is not considered as a dangerous chemical substance, therefore its use under environmental aspects makes this accelerator extremely advantageous in terms of product handling and processing.


In formulations based on liquid bisphenol A epoxy resins (EEW 182-192) and micronized dicyandiamide, Dycure U500-21 is typically added in amounts of less than 5 parts per 100 parts of epoxy resin. The optimal ratio strongly depends on the specific application and process requirements and has to be determined individually for each case.


Its good latency properties make Dycure U500-21 ideal for storage-stable one-component formulations. Depending on fillers, modifiers and storage temperature, a shelf life of up to 2 months at room temperature may be obtained.


Compared to many other urea type accelerators, Dycure U500-21 shows a superior acceleration performance. Curing is possible at temperatures as low as 80°C.


OTHER RECOMMENDATIONS


Being a bi-functional uron, Dycure U500-21 is able to cure liquid epoxy resins without the use of dicyandiamide curing agents. In mixing ratios of less than 10%, Dycure U500-21 cures at temperatures from 80°C to120°C forming dense polymer networks which show normal to slightly “flexible” mechanical properties. In addition, formulations with Dycure U500-21 as a curing agent show very favorable enthalpy developments during the curing process. Therefore Dycure U500-21 is especially suited for thick layered glass or carbon fiber laminates.


ADVANTAGES

  • Shows one of the highest reactivity amongst the entire Dycure uron product family

  • Although very reactive, latencies of 2months (at 23°C) are achievable

  • Low in toxicity, not corrosive, not skin irritant

  • Can be used as accelerator and curing agent

  • Moderates enthalpy development in curing processes when used as sole curing agent.


TYPICAL APPLICATIONS


Dycure U500-21 is widely used as accelerator to activate dicyandiamide curing agents in various single component thermosetting epoxy resin formulations for:

  • Composites based on prepregs e.g., in wind energy, automotive, machinery and aerospace industry

  • Encapsulation compounds in the electronic industry

  • Reinforcements in the automotive industry

Dycure U500-21 is used as a sole curing agent in one-component the thermosetting epoxy resin formulations for:

  • Composites based on prepregs with low enthalpy development

  • Laminates in thick layers


HEALTH & SAFETY PRECAUTIONS


Dycure U500-21 is classified as low toxic and has neither primary skin nor eye irritant properties. Nevertheless, being a fine powder, precautions for dust must be observed. For additional health and safety information, please refer to the actual Material Safety Data sheet.


PACKAGING & STORAGE


Dycure U500-21 is available in 10kg cartons, 400kg/PAL.

Long storage and humidity may result in caking. Keep packaging tightly closed. Storage time from date of delivery is recommended not to exceed 6 months.

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