Liquid, resinous epoxy resin hardeners - from aromatic polyamines reacted with cpds. contg. active aldehyde gps.

摘要

An aromatic polyamine (e.g. o-, m-, or p-phenylene diamine) is dissolved in water, isopropyl alcohol or dil. acid or alkali, and an active aldehyde cpd. (e.g. formaldehyde, acetaldehyde) is added in molar ratio to polyamine of 1:1.5-10. The temp. is kept at 25-100 degrees C until the reaction is ended, the water removed and the product heated at 150 degrees C in vacuum for 0.5-4 h. Pref. half the polyamine is used initially and the remainder added after removing the water. The polyamine is pref. m-phenylene diamine, the aldehyde is HCHO or acetaldehyde and the solvent is isopropyl alcohol. The complex. mixts. obtained are liquids which do not crystallise on standing and hence can be easily mixed into liquid epoxy resins without pre-heating or diluting. The viscosity can be varied to suit that of the epoxy resin, by choice of ingredients, ratios and processing conditions. The resins have excellent oxidation resistance and thermal stability.