The present invention provides a catalyst for
polyester production capable of producing a
polyester with high catalytic activity and a process for producing a
polyester using the catalyst. The catalyst for polyester production comprises a
solid titanium compound which is obtained by dehydro-
drying a hydrolyzate obtained by
hydrolysis of a
titanium halide and which has a
molar ratio (OH / Ti) of a hydroxyl group (OH) to
titanium (Ti) exceeding 0.09 and less than 4. The present invention also provides a method to obtain a polyester having a small increase of the
acetaldehyde content during the molding. This method comprises bringing a polyester, which is obtained by the use of a titanium compound catalyst and in which the reaction has been completed, into contact with a phosphoric ester
aqueous solution or the like having a concentration of not less than 10 ppm in terms of
phosphorus atom. The present invention further provides a polyester having excellent transparency and tint and molded products of the polyester such as a blow molded article, a film, a sheet and a
fiber. The polyester is obtained by polycondensing an aromatic
dicarboxylic acid or an ester-forming derivative thereof and an aliphatic
diol or an ester-forming derivative thereof in the presence of a catalyst for polyester production which comprises a polycondensation catalyst component comprising a
solid titanium compound and a co-catalyst component comprising a
magnesium compound. This polyester has a titanium content of 1 to 100 ppm, a
magnesium content of 1 to 200 ppm and a weight ratio (Mg / Ti) of
magnesium to titanium of not less than 0.01.