GB840334A - A process for the production of synthetic resins - Google Patents

Abstract

Epoxy resins containing one or more epoxide groups per mol. and which may be hardened by means of acid or basic substances, e.g. amines, organic acid anhydrides, sulphochlorides, sulphonic acids or Friedel-Crafts catalysts, are obtained by reacting at least 2 mols. of an epoxy halide with 1 mol. of an acid salt of an aromatic hydroxy- or mercapto-carboxylic acid in a medium which does not contain more than catalytic amounts of water. Alkali, alkaline earth or ammonium salts or salts of tertiary organic bases are suitable. In addition to carboxyl, hydroxyl or mercapto groups, which may be on the same or different nuclei of the acid, the aromatic rings may carry other substituents, e.g. alkyl, halogen or methoxy groups; the hydroxy, mercapto or carboxyl groups need not be linked directly to the aromatic nucleus. Thus hydroxymethyl- or mercaptomethyl-benzoic acid may be used. Other acids specified are o-, m- or p-hydroxybenzoic, or the corresponding mercaptocarboxylic acids, or of hydroxy or mercapto carboxylic acids derived from naphthalene, anthracene, diphenyl, diphenyl ether, diphenyl sulphide, diphenylmethane, dibenzophenone, diphenyl sulphone, diphenylsulphoxide and alkyl diphenylamines. Suitable epoxy halides are epichlorhydrin, epibromhydrin, and 1-chloro-3,4-epoxybutane. 320 gs. Na p-hydroxybenzoate were suspended in 150 gs. epichlorhydrin containing 2.5 gs. dimethylaniline and the mixture refluxed at 117-123 DEG C. for 11 hours. The light yellow resin obtained after filtering off excess epichlorhydrin was melted with 0.8-1 part of maleic or phthalic anhydride and placed between aluminium plates and heated to 10-20 hrs. at 140 DEG C. In a similar manner a hardening mixture of dibutyl phthalate and diethylenetriamine was employed. The initial reaction may be performed in an inert solvent, e.g. a ketone, chlorinated hydrocarbon or ether. The products may be used as binding materials, casting or moulding resins, laminates or lacquers.