A process for reacting an acidic compound or anhydride with an epoxy-containing compound is disclosed. In a preferred embodiment this process comprises reacting a polyepoxide having more than one vic-epoxy group with a phenol in the presence of a methylene bis(triphenylphosphonium)halide catalyst.
The process of reacting an epoxy resin with a reactive hydrogen-containing compound or a carboxylic acid anhydride in the presence of a phosphonium catalyst is improved by employing a phosphonium compound having an amino substituent on the cation portion of the phosphonium compound as the catalyst. The invention also concerns precatalyzed epoxy resin compositions, curable compositions and cured compositions.
Advancement catalysts which are a combination of a phosphonium halide or an alkylene phosphorane and a nitrogen heterocycle selected from the group consisting of substituted or unsubstituted imidazoles, benzimidazoles, imidazolines, dihydropyrimidines, tetrahydropyrimidines, dihydroquinazolines, their salts and mixtures thereof, confer high reactivity and selectivity on epoxy resin advancement reactions. The advanced epoxy resins are useful in the preparation of coatings of high quality.
The products resulting from contacting an organic phosphine or arsine with an inorganic acid having a weak nucleophilic anion provide for relatively stable compositions when admixed with a compound containing an average of more than one vicinal epoxide group per molecule and which optionally contains a compound containing an average of more than one phenolic hydroxyl group per molecule.
According to the invention, a relatively low molecular weight epoxy resin is reacted with a hydroxyl group-containing compound in the presence of a bis(trihydrocarbyl phosphine)iminium salt catalyst to produce a high molecular weight fusion reaction product. The process is particularly useful in reacting an epoxy resin having a molecular weight of less than about 500 with bisphenol-A in the presence of a bis(phosphine)iminium halide to produce a fusion reaction product having a molecular weight within the range of about 500 to 7000. The catalyst is relatively water-insensitive, and the reaction can therefore be carried out in the presence of water.
Poly(hydroxy ethers) are prepared by reacting a dihydric phenol with a diepoxide in the presence of a catalyst selected from the group consisting of bis(trihydrocarbylphosphoranylidene)ammonium salt, bis[tris(dihydrocarbylamino)phosphoranylidene]ammonium salt, and tetrakis[tris(dihydrocarbylamino)phosphoranylideneamino]phosphonium salt. The reaction between the dihydric phenol and the diepoxide is conducted in an ether or hydroxy ether solvent at a temperature sufficiently high to produce a poly(hydroxy ether). Polymers prepared by the new process are more highly branched than those produced by known methods.
