Catalyst for polyester production, process for producing polyester using the catalyst, polyester obtained by the process, and uses of the polyester

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.