Classification and selection of curing agents

The curing agent can be divided into normaltemperature curing agent and heating curing agent according to the application.Epoxy resins generally have good properties when cured at high temperatures,but coatings and adhesives used in civil construction need to be cured at roomtemperature due to difficult heating; therefore, fatty amines, cycloaliphatics,and polyamides are mostly used, especially those used in winter. Coatings andadhesives have to be used in combination with polyisocyanates, or polyalcoholswith an offensive odor.

The type of curing agent has a great impact on themechanical properties, heat resistance, water resistance, and corrosionresistance of the cured product. For example, curing agents such as aromaticpolyamines, imidazoles, and anhydrides have higher heat resistance than epoxyresins. Polyamine, low molecular weight polyamide curing agent; aromatic acidanhydride cured epoxy resin has better water resistance than aromatic diamineand aliphatic polyamine curing agent   curing agent has good alkali resistance, butacid resistance and resistance. Alicyclic polyamine cured epoxy resin hasexcellent resistance. The acid resistance of acid anhydride cured epoxy resinis better than acid resistance. The appropriate curing agent should be selectedaccording to different applications and performance requirements.

Curing agent selection:

The curing agent has a great influence on theperformance of epoxy resin. Generally, it is selected according to thefollowing points:

(1) Select from performance requirements: some requirehigh temperature resistance, some require good flexibility, and some requiregood corrosion resistance, then select an appropriate curing agent according todifferent requirements.

(2). Choose from curing methods: Some products cannotbe heated, so you cannot use heat curing curing agents.

(3). Choose from the applicable period: The so-calledperiod refers to the period from when the epoxy resin is added to the curingagent to when it cannot be used. To apply for a long period of time, acidanhydrides or latent curing agents are generally used.

(4) Choose from safety: Generally, it is better tohave low toxicity, which is convenient for safe production.

(5) Choose from cost