GB806195A - Improvements in or relating to the hardening of epoxy resins - Google Patents

Abstract

Epoxide resins are cured by heating the epoxy resin with a liquid condensation product of an aliphatic polyamine and a saturated aliphatic monocarboxylic acid or corresponding amino acid, containing 2-10 carbon atoms in the molecule, the condensate containing free amino groups and being obtained by mixing the polyamine and acid in proportions of at least one mol. polyamine per mol. acid and heating the mixture to first remove the elements of water and then further under reduced pressure to remove residual polyamine. Acids specified are acetic, propionic, butyric, valeric, caproic, enanthic, caprylic, pelargonic, capric, 2-ethyl hexoic, amino-caproic; their acid halides or alcoholic esters may also be used; dicarboxylic acids may be present in minor amounts. 2 mols. triethylene tetramine and 1 mol. 2-ethyl hexoic acid were heated to 235 DEG C. in an atmosphere of nitrogen; a low vacuum was applied and the temperature allowed to fall to 180 DEG C. during which period a syrupy distillate was removed; distillation was continued under a vacuum of 26 inches, 15 gs. of the residual liquid was mixed with 45 gs. of an epoxy resin and 7 gs. dibutyl phthalate; the mixture set in four days to a tough solid.ALSO:Liquid amides containing free amino radicals are prepared by reacting at least one mol., preferably one to two mols., of an aliphatic polyamine with a C2-10 saturated aliphatic monocarboxylic acid or an amide-forming derivative thereof, e.g. an acid halide or an aliphatic alcohol ester, subjecting the resulting salt to heat treatment to remove the elements of water and to further heat treatment under reduced pressure to remove any residual polyamine. The heat treatment is preferably carried out under nitrogen and the recovered polyamine is recycled for re-use. The polyamine is such as to furnish liquid reaction products and is exemplified by triethylene tetramine. The carboxylic acid may be a fatty acid, such as acetic, propionic, butyric, valeric, caproic, enanthic, caprylic, pelargonic and capric acids, a branched-chain acid, such as 2-ethyl-hexoic acid, or an amino acid, such as aminocaproic acid. Mixtures of the above acids may be employed and the above acids may also contain minor amounts of dicarboxylic acids such as sebacic acid. In examples triethylene tetramine is condensed with (1) acetic acid; (2) capric acid; and (3) 2-ethyl-hexoic acid. The Provisional Specification refers to the use of ethylene diamine and diethylene triamine as polyamine reactants and to the use of linoleic acid to form mono- and diamide derivatives.