| 摘要 |
3. A curing agent for epoxy resins in the form of a composition of liquid aromatic amines containing 4,4'-diaminodiphenylmethane in pure form or as a technical product, toluene derivatives in the form of a waste product of the production of 2,4 and 2,6 toluylenediamines and possibly a tertiary amine of the Mannich base type, characterised in that in 100 parts by weight of 4,4'-diaminodiphenylmethane or its technical product, it contains from 100 to 500 parts by weight of the mixture of symmetric toluylenediamines, which constitute the post-production waste of the process of the production of 2,4 and 2,6 toluylenediamines, containing preferably 20 percent of 2,4 and 2,6 toluylenediamines and 80 percent of 2,3, 3,4 and 2,5 toluylenediamines in a weight ratio of 3:3:4 and from 30 to 100 parts by weight of salicylic acid and 300-1000 parts by weight of aromatic, aromatic-aliphatic and/or cycloaliphatic solvent, e.g. benzyl alcohol, and possibly biphenyl A epoxy resin with epoxy number from 0.1 to 0.52 gram-equivalent of epoxy groups/100 in a quantity of 1 to 10 parts by weight in proportion to 100 parts by weight of the mixture of amines and/or possibly a tertiary amine of the Mannich base type in a quantity of 0.1 to 20 parts by weight.
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