bicarboxylic acid, or a dialkyly esterthered, with an aliphatic diol with 2-12 carbonatoms.Terephthalic acid and naphthalenedicarboxylic acids, or their dimethylic esters, are representative compounds.Examples of aliphatic diols are ethylene glycol, 1,4-butandiol and 1,4-dimethylolcycloexan.Preferred polyester resins are polyethyleneterephthalate, polybuthyleneterephthalate and polyalkyleneterepht