Dicyandiamide curing agent belongs to the heating curing class of latent curing agent, solid at room temperature, insoluble in epoxy resin, dispersed in epoxy resin in the form of microparticles, through the heating reaction, once heated to the melting point of the vicinity of the start of the dissolution and rapid reaction curing.   Curing reaction of dicyandiamide The molecular structure of dicyandiamide contains a cyano group (-CN) in addition to four active hydrogens. Cyano group can also participate in the curing reaction as a functional group. The curing reaction temperature of dicyandiamide is generally in the range of 160~180°C, and the curing reaction time is 20~60 minutes. For bisphenol A epoxy resin with 190 epoxy equivalents, the theoretical dosage of dicyandiamide curing agent (calculated on the basis of active hydrogen equivalents) is 11.1 parts, but the actual dosage is often in the range of 4-10 parts (based on 100 parts of the resin by mass). Dicyandiamide micropowder is dispersed into the epoxy resin, has a suitable storage period, is stable in storage, does not delaminate, and does not cure.   The fineness of the dicyandiamide particles may vary from product to product. The finer the dicyandiamide particles, the more obvious the performance advantage for curing reaction Ultra-fine dicyandiamide particles are easier to be evenly dispersed into the epoxy resin liquid. Ultra-fine dicyandiamide particles can be better mixed and dissolved in the epoxy resin liquid than ordinary dicyandiamide.   Application areas of dicyandiamide curing compounds Dicyandiamide epoxy resin has good adhesive property, heat resistance and stable storage period. Dicyandiamide epoxy resins can be widely used in powder coatings, carbon fibre prepregs, heat curable inks, laminates, single component adhesives and other applications. Typical applications: Preparation of prepregs for the manufacture of reinforced composites (wind energy, automotive, aerospace, marine engineering and other industries). Electronic packaging materials, adhesives. Powder coatings (especially heavy duty anti-corrosion function). For epoxy-based adhesives (reinforced materials).   Nanjing Yolatech provides all kinds of high purity and low chlorine epoxy resins, including Bisphenol A epoxy resin, Bisphenol F epoxy resin, Phenolic epoxy resin, Brominated epoxy resin, DOPO modified phenolic epoxy resin, MDI modified epoxy resin, DCPD epoxy resin, Multifunctional epoxy resin, Crystalline epoxy resin, HBPA epoxy resin and so on. And we also could provide all kinds of curing agents or hardeners and diluents.   We will be at your service 24 hours a day. Pls contact us freely.    

Epoxy resin adhesive is a reprocessing or modification of epoxy resin to make its performance parameters meet specific requirements. Usually epoxy resin adhesives are also used with curing agents and need to be mixed well to be fully cured. Generally, the epoxy resin adhesive is called A adhesive or main agent, and the curing agent is called B adhesive or curing agent(hardener).   Main properties of epoxy resin adhesives before curing Colur, viscosity, specific gravity, proportioning, gel time, open time, curing time, thixotropy (flow stopping), hardness, surface tension, etc.   Main properties of epoxy resin adhesive after curing Resistivity, proof voltage, water absorption, compressive strength, tensile strength, shear strength, peel strength, impact strength, heat deflection temperature under load, glass transition temperature, internal stress, chemical resistance, elongation, shrinkage coefficient, thermal conductivity, electrical conductivity, weathering resistance, aging resistance, dielectric constant.   Curing characteristics of epoxy resin adhesive Most of the epoxy resin adhesives are heat-setting adhesives. The higher the temperature of the epoxy resin adhesive, the faster the curing. The more the amount mixed at one time, the faster the curing. The curing process has exothermic phenomenon, etc.   Nanjing Yolatech provides all kinds of high purity and low chlorine epoxy resins, including Bisphenol A epoxy resin, Bisphenol F epoxy resin, Phenolic epoxy resin, Brominated epoxy resin, DOPO modified phenolic epoxy resin, MDI modified epoxy resin, DCPD epoxy resin, Multifunctional epoxy resin, Crystalline epoxy resin, HBPA epoxy resin and so on. And we also could provide all kinds of curing agents or hardeners and diluents. We will be at your service 24 hours a day. Pls contact us freely.  

Background Under normal conditions, bisphenol A-type liquid epoxy resins are colorless, transparent and flowable. When the external temperature is lowered, the molecular chain is less active and prone to crystal seeding. Liquid epoxy resin appears grey in color, free-floating crystals, crystal clusters, or hard lumps like curing, we call it the crystallization phenomenon.   Reasons for the crystallization of epoxy resin The reasons for the crystallization of epoxy resin are complex, we mainly summarize the following. High purity. We all know that crystals are highly pure substances, and so is epoxy resin, the higher the purity, the narrower the molecular distribution, the easier it is to crystallize. Low viscosity. The lower the viscosity, the faster the crystallization. Impurities. solid impurities are usually crystalline species for crystal growth, and the addition of certain precipitating pigment fillers can easily lead to crystallization. In contrast, larger particle sizes and higher additions are less likely to induce crystallization. Temperature. A narrow temperature cycle of 20-30°C is a common cause of crystallization, with diurnal temperature fluctuations initiating or accelerating the rate of crystallization. In addition, ultra-low temperatures (below 5°C) will accelerate crystallization. Moisture. The higher the moisture content, the more likely crystallization will occur.   Does crystallization affect the properties of epoxy resins? The crystallization phenomenon does not affect the performance of the epoxy resin, only the epoxy resin morphology has changed, not deterioration. However, it brings a lot of inconvenience to the operation. After practice, the crystalline epoxy resin is dissolved by heating and mixed with the corresponding proportion of curing agent, its tensile strength, flexural strength, compressive strength, and bonding strength have no change in comparison with epoxy resin without crystallization. It can be seen that the crystallization phenomenon does not affect the performance of the epoxy resin, only the epoxy resin morphology has changed, not a qualitative change. In general, the crystallization of epoxy resin adhesive is a reversible process that can be changed with the temperature and has no effect on the bonding performance and reinforcing effect of epoxy resin cured products. Even if the crystallization occurs, heating until it softens and disappears, it can be used normally.   Nanjing Yolatech provides all kinds of high purity and low chlorine epoxy resins, including Bisphenol A epoxy resin, Bisphenol F epoxy resin, Phenolic epoxy resin, Brominated epoxy resin, DOPO modified phenolic epoxy resin, MDI modified epoxy resin, DCPD epoxy resin, Multifunctional epoxy resin, Crystalline epoxy resin, HBPA epoxy resin and so on. If you are interested in them, pls kindly contact us. We will be at service for you any time, thank you.