Hydroxyethylethylenediamine, also known as curing agent 1, has a molecular formula of C4H12ON2 and a relative molecular weight of 104.15. CAS：111-41-1，The structural formula is H2NCH2CH2NHCH2CH2OH, which appears as a light yellow to yellow viscous liquid with an ammonia odor and is non irritating. Soluble in water and ethanol, easily hygroscopic, able to absorb carbon dioxide and water from the air, and has good compatibility with epoxy resin. Volatility is smaller than ethylenediamine, viscosity is slightly higher than ethylenediamine, and toxicity is reduced by 6-7 times compared to ethylenediamine. Commonly used as a curing agent for epoxy resins, it has the characteristics of low toxicity and room temperature curing.