Abstract: This invention relates to a process for producing polyester fibers with enhanced dyeability, lesser elongation and greater strength, which comprises combining 2-methyl-1,3-propanediol into a mixture containing terephthalic acid, or an alkyl ester thereof, and a (C.sub.2-6)alkanediol, and carrying out polymerization. The resultant polyester copolymer is then spun to produce polyester fibers. This invention also relates to the polyester fibers produced by this process. These polyester fibers exhibit enhanced dyeability, lesser elongation and greater strength than un-improved polyester fibers.

Abstract: Poly(butylene terephthalate) is prepared in a two-stage process wherein terephthalic acid and 1,4-butanediol are esterified in the presence of a catalytic amount of a catalyst having an organo-metallic component which is an organo-titanate compound, an organo-tin compound or a combination thereof and a salt component which is an organic acid salt or an inorganic salt. In a second step, the esterification product is subject to polycondensation. By following the foregoing procedure, the formation of tetrahydrofuran is significantly suppressed and the percent conversion of esterification products increased.