GB897096A - Process for the production of epoxide resins - Google Patents

Abstract

Epoxy resins are obtained by hardening epoxy compounds obtained by reacting an organic compound containing one carboxyl group and one phenolic hydroxyl group at elevated temperature with a haloepoxyalkane containing halogen adjacent to the epoxide group (for preparation see Group IV(b)), using any compound suitable as a hardener for epoxide resins, for example with organic bases or with poly-carboxylic acids or their anhydrides. In an example, an epoxide resin obtained by heating p-hydroxybenzoic acid, epichlorhydrin and a heat-hardened melamine resin, is mixed with a mixture of phthalic anhydride and tetrahydro-phthalic anhydride and hardened at 140 DEG C. for 14 hours; the epoxide resin is also mixed with a polyamide containing free amino groups and hardened at 100 DEG C. or at room temperature; dibutyl phthalate may be added to the resin-hardener mixture before hardening.ALSO:Hardenable compounds containing epoxide groups are made by reacting an organic compound which contains in the molecule one carboxyl group and also one phenolic hydroxyl group at elevated temperature with a haloepoxyalkane containing a halogen atom adjacent to the epoxide group in a quantity of more than 4 mol per mol of the phenolcarboxylic acid, in the presence of a polymeric catalyst insoluble in the reaction mixture, said catalyst containing either (a) a saltlike group, (b) a group which may be converted into a salt-like group under the conditions of the reaction, or (c) an acid amide group, with subsequent separation of the catalyst and distillation of the excess haloepoxyalkane and volatile products of the reaction. Suitable catalysts include salts of polyacrylic acid, ion exchange resins, such as cation and anion exchange resins, in the form of their salts, amphoteric ion resins, polyamides, polymeric organic bases, aminoplasts such as melamine resins or urea resins; epoxide resins hardened with organic amines; polymers containing divalent sulphur atoms, which with haloepoxyalkanes may be converted into ternary sulphonium compounds; ammonium alginate. Suitable starting materials include salicylic acid, meta and para hydroxybenzoic acids, hydroxynaphthoic acids and p-hydroxyphenylacetic acid; reaction products of monoalkali metal salts of dihydric phenols with salts of halocarboxylic acids or a dicarboxylic anhydride; products from maleic anhydride, a phenol and an alcohol; esters formed from two or more molecules of a phenolcarboxylic acid. Epichlorohydrin is the preferred haloepoxyalkane. Reaction temperatures generally lie between 60 DEG C. and 200 DEG C., and when using epichlorohydrin in large excess, the reaction mixture may be boiled under reflux. The products may be hardened with suitable hardeners, and may be used as adhesives, casting resins or lacquer resins (see Group IV(a)).