hydroxy functional polyester oligomer can also be obtained using a second synthesis procedure in which a poly glycidyl ester compound is reacted with a tertiary acid derivative the epoxy ester containing compound can be obtained by epoxidation of the above mentioned polycarboxylic acid derivatives examples of epoxy ester derivatives are hexahydrophthalic acid di glycidyl ester trimellitic acid tri glycidyl ester polyglycidyl ester of the adducts of tmp and or mpe with hhpa and or mhhpa or mixtures thereof in an alternative reaction procedure the epoxy ester containing compounds can be reacted with tertiary acid components to yield the described hydroxy functional polyester derivatives examples of the tertiary acid components are pivalic acid dimethylol propionic acid hydroxy pivalic acid a catalyst can be used to accelerate ring opening esterification reactions usually employed are organotin catalysts such as dibutyltindilaurate dibutyltinoxide tinoctoate and the like tri substituted amines such as triethylamine dimethyl benzylamine dimethyl ethanolamine triethanolamine and the like tertiary amine salts such as benzyltrimethylammonium hydroxide tetrabutylammonium iodide and the like phosphonium containing catalysts such as ethyltriphenylphosphonium iodide ethyltriphenylphosphonium bromide and the like the catalyst is optional and if used the amount added can vary widely when used the amount typically ranges from about 0 01 to 1 weight percent based on binder solids the described binder systems are utilized to produce coatings by blending with other suitable components in accordance with normal paint formulating techniques the.