Characteristics of dicyandiamide curing agent

Characteristics of dicyandiamide curing agent

Dicyandiamide curing agent belongs to the earliest used type of heat-curing self-limiting curing agents. It is in solid state at room temperature and does not dissolve in epoxy resin. It is dispersed in epoxy resin in the form of dust particles and then reacts with heat. Once the temperature is heated to around the melting point, it gradually melts and rapidly reacts to cure.

Dicyandiamide is a white crystalline powder with a melting point at 209℃. It can partly dissolve in boiling water, ethyl acetate, toluene, and dimethylformamide, but is insoluble in xylene.

Application of dicyandiamide curing agent:

Dicyandiamide micro powder is dispersed in epoxy resin, and the storage stability can be maintained for more than 6 months without separation or curing. The curing reaction temperature is generally at 160~180℃, and the curing reaction speed is 20~60min. The basic theoretical use amount of dicyandiamide curing agent (measured by Langlois hydrogen agent method) for 190 parts of bisphenol A epoxy resin is 11.1 parts, but the actual use amount is often within the range of 4~10 parts (based on 100 parts of epoxy resin quality).

Characteristics of dicyandiamide curing agent:

Dicyandiamide curing agent belongs to the earliest used type of heat-curing self-limiting curing agents. It is in solid state at room temperature and does not dissolve in epoxy resin. It is dispersed in epoxy resin in the form of dust particles and then reacts with heat. Once the temperature is heated to around the melting point, it gradually melts and rapidly reacts to cure.

Promoter of dicyandiamide curing agent:

The main disadvantage of the curing of dicyandiamide is its high curing temperature. In order to better reduce the curing temperature of dicyandiamide, improve its curing rate, and improve its compatibility with epoxy resin, various promoters are usually used together with dicyandiamide. Since the use of promoters reduces the applicable period and harms the storage stability, it is important to select suitable promoters based on technical requirements.

The promoters of dicyandiamide are mostly alkaline chemical substances, including imidazolines and their compounds, organic chemical ureas, modified materials such as acrylamides, and hydrazide compounds.

Characteristics of dicyandiamide cured products:

Dicyandiamide epoxy resin cured products have excellent bonding properties and Tg temperature, and do not discolor. However, the waterproofing performance of dicyandiamide curing agent is poor, so the amount of dicyandiamide used should be adjusted according to the performance testing scheme in specific applications.

Main applications of dicyandiamide:

Dicyandiamide epoxy resin can be widely used in electrostatic powder coating, carbon fiber material pre-impregnated materials, thermosetting printing inks, fiberglass boards, one-component adhesives and other industries.