Dicyandiamide, also known as dicyandiamide, cyanoguanidine, or DICY for short.
Structural formula of dicyandiamide:
Characteristics of dicyandiamide curing agent:
Dicyandiamide curing agent belongs to the earliest latent curing agent of heating curing. It is solid at room temperature, insoluble in epoxy resin, dispersed in epoxy resin in the form of fine particles, and then heated to react. Once heated to the melting point, it begins to dissolve and quickly reacts to cure. Dicyandiamide is a white crystalline powder with a melting point of about 209℃, which can be partially dissolved in hot water, ethanol, acetone and dimethylformamide, but insoluble in toluene.
Use of dicyandiamide curing agent：
Dicyandiamide micro-powder dispersed in epoxy resin can be stored for more than 6 months, which is stable, non-delamination and non-curing. The curing reaction temperature is generally 160~180℃ and the curing reaction time is 20~60 minutes. For bisphenol an epoxy resin with an epoxy equivalent of 190, the theoretical dosage of dicyandiamide curing agent (calculated by active hydrogen equivalent) is 11.1 parts, but the actual dosage is often in the range of 4-10 parts (based on 100 parts of resin).
Accelerator of dicyandiamide curing agent：
The curing temperature of dicyandiamide is high, which is its biggest disadvantage. To reduce the curing temperature of dicyandiamide, improve its curing speed and improve its compatibility with epoxy resin, dicyandiamide is usually used together with various accelerators. Because the use of accelerators will shorten the shelf life and affect the storage period, it is very important to choose suitable accelerators according to the process needs. The promoters of dicyandiamide are mostly alkaline compounds, and the commonly used promoters include imidazole and its derivatives, organic urea, modified amine and hydrazide.
Characteristics of dicyandiamide cured product:
The cured dicyandiamide epoxy resin has good adhesion and Tg temperature and is not colored. However, the water resistance of dicyandiamide curing agent is not good, so the dosage of dicyandiamide can be adjusted according to the performance requirements in practical application.
Application fields of dicyandiamide:
Dicyandiamide epoxy resin can be widely used in powder coatings, carbon fiber prepregs, thermosetting inks, laminates, one-component adhesives, and other fields.
