GB1095663A - Polyesterimide resins - Google Patents

Abstract

Thermosetting polyesterimides are prepared by interacting (a) a polybasic carboxylic acid having at least 3 carboxyl groups attached to an aromatic ring or a reactive derivative thereof, (b) a C2- 6 glycol and (c) a poly-primary amine or reactive derivative thereof in the presence of a surplus of the glycol at least part of the surplus being separated by distillation after polycondensation. Polybasic carboxylic acids specified are trimellitic, and pyromellitic. Terephthalic acid may also be present. Pentaerythritol is specified as a polyhydric alcohol. The polyvalent primary amine may be aromatic, e.g. 4,41-diamino-diphenylmethane. Glycols specified are ethylene glycol, propane-1,2 and 1,3-diols, butylene glycol and diethylene glycol. The reactants (a) to (c) may be used in an at least 20% solution in the glycol to give at least 1 mole surplus of glycol for every ester link in the product. The polymerization may be carried out in the presence of hydroxycarboxylic acids, aminocarboxylic acids, amino-alcohols, polyvalent primary amines containing secondary amino-groups and catalysts, e.g. tin oxalate, Sb2O3 or a titanium compound. A fractionating column may be used to ensure that water only is distilled from the system during polycondensation, the glycol being removed afterwards. In the latter case a reduced pressure may be used. Between removal of the water and removal of the glycol a mixture of pigments, e.g. TiO2, Fe2O3, talcum mica, a consolidating agent, e.g. silica gel or dimethyl di-octa-decyl ammonium montmorillonite and a glycol may be added. The product of the reaction is soluble in cresol/xylol/ aromatic hydrocarbon mixtures. It may be used for coating, e.g. wire insulation, mouldings, laminates, films, foils, spin sintering and flame-spraying. The condensed ethylene glycol may be reused as starting material. In Example (3), a condensate of aniline and formaldehyde in the presence of HCl functions both as a polyamine and as a polyhydric alcohol.ALSO:A polyesterimide useful for coating is prepared by reacting a polybasic carboxylic acid having at least 3 carboxyl groups joined to a benzene ring with a C2-6 glycol and a poly-primary amine, the glycol being present in excess and some of the excess being distilled off after polycondensation. The resin may be applied to electrical copper wiring, or woven fibres in solution or by flame spraying or spin sintered spraying. The resin may be hardened at 180 - 200 DEG C. In Examples: (1) a polymer derived from terephthalic acid, pentaerythritol, ethylene glycol, diaminodiphenylmethane and trimellitic anhydride in the presence of tin oxalate and Sb2O3 is applied to metal sheet; (2) the polymer of Example 1 dissolved in a mixture of cresol, xylol and naphtha is applied to copper wire; (3) a condensate of an aniline/formaldehyde resin, ethylene glycol and trimellitic anhydride dissolved in cycolhexane, DMF, DMA and furfuryl alcohol is used to impregnate electrical windings and (4) a polymer of trimellitic anhydride, ethylene glycol and diaminodiphenylmethane dissolved in excess ethylene glycol is also used to impregnate electrical windings.