Dicyandiamide as a Latent Epoxy Curing Agent
Dicyandiamide (DCD; CAS 461-58-5) is the workhorse latent curing agent for epoxy resins. Its defining property is latency: a mixture of epoxy resin and dicyandiamide is stable at room temperature, often for months, but cures rapidly when heated. That behaviour is the basis of one-part epoxy adhesives, coatings, laminates and prepregs.
This article looks at how dicyandiamide is used in epoxy curing and why it is so widely chosen. For the chemistry and specifications, see our overview of dicyandiamide: properties, manufacturing and applications.
What “Latent Curing Agent” Means
A curing agent (hardener) crosslinks the epoxy resin. In a two-part system the hardener reacts as soon as it is mixed, so the user has a limited “pot life” and must use the mix quickly. A latent curing agent like dicyandiamide is different:
| Feature | Two-part system | Dicyandiamide (latent) system |
|---|---|---|
| Formulation | Two components, mixed at use | One component, pre-mixed |
| Storage life | Short once mixed | Long – stable until heated |
| Cure trigger | Mixing | Heat |
| Pot life | Limited | Not applicable (cures on heating) |
| Convenience | Requires mixing and metering | Ready to use |
This is why dicyandiamide is chosen for one-part epoxies: the formulator premixes a stable product, and the end user simply applies it and heats it to cure.
Why Dicyandiamide Is Chosen
- Long latency – gives one-part systems a long shelf life at room temperature.
- Heat-triggered cure – cures reliably once the required temperature is reached.
- Good cured properties – produces hard, chemically resistant, well-crosslinked networks.
- Solid, easy to incorporate – supplied as a fine powder and dispersed into the resin.
- Versatile – used across adhesives, coatings, laminates and composites.
Accelerators: Lowering the Cure Temperature
Dicyandiamide alone cures at relatively high temperature. In practice it is almost always combined with an accelerator (for example a substituted urea or an imidazole) to bring the cure temperature down to a practical level for the process. The choice of accelerator and its level control the cure schedule and the final properties.
| Component | Role |
|---|---|
| Dicyandiamide | Latent curing agent (crosslinker) |
| Accelerator | Lowers activation temperature; speeds cure |
| Filler / additives | Adjusts viscosity, flow, conductivity or strength |
Where Dicyandiamide-Cured Epoxy Is Used
| Application | Why a latent system fits |
|---|---|
| One-part structural adhesives | Long shelf life; cures on heating in the assembly process |
| Prepregs and laminates | Stable before cure; cures during hot pressing or autoclaving |
| Coatings | One-part coatings that cure on baking or in service heat |
| Composites | Latency suits the lay-up-and-cure workflow |
| Electronics and electrical | Reliable, controlled cure for encapsulants and laminates |
Handling and Sourcing Notes
| Consideration | What to confirm |
|---|---|
| Assay | 99% min, as stated on the COA |
| Particle size | Matched to the dispersion requirement of the formulation |
| Moisture and impurities | Within specification; low residual cyanamide where relevant |
| Documentation | COA and SDS |
Frequently Asked Questions
Why is dicyandiamide used as an epoxy curing agent?
Because it is latent: an epoxy-dicyandiamide mix is stable at room temperature and cures on heating, which enables one-part adhesives, coatings, laminates and prepregs with long shelf life.
Does dicyandiamide cure epoxy at room temperature?
No. Dicyandiamide requires heat to cure. It is usually combined with an accelerator to bring the cure temperature down to a practical level.
What accelerator is used with dicyandiamide?
Commonly substituted ureas or imidazoles. The accelerator and its level set the cure schedule and the final properties of the cured epoxy.
How much dicyandiamide is used in an epoxy?
The level depends on the resin and the cure target and is set by formulation and testing; it is usually a few parts per hundred of resin.
Is dicyandiamide the same as cyanoguanidine?
Yes. Dicyandiamide (CAS 461-58-5) is also called cyanoguanidine and 1-cyanoguanidine; these are the same compound.
How do I buy dicyandiamide?
PolyBlueChem supplies dicyandiamide (CAS 461-58-5) at 99% min with a full Certificate of Analysis. Contact our team for specifications and a quotation.