Patent ID: 7179869

Claim:
A process for producing a polyester resin comprising dicarboxylic acid constitutional units and diol constitutional units wherein 5 to 60 mol % of the diol constitutional units have a cyclic acetal skeleton, said process comprising: an oligomerization step for transesterifying an ester D having an acid value of 30 μeq/g or lower represented by the formula 1: wherein R 1 , R 2 and R 3 are each independently a divalent hydrocarbon group selected from the group consisting of C 1 to C 10 aliphatic hydrocarbon groups, C 3 to C 10 alicyclic hydrocarbon groups and C 6 to C 10 aromatic hydrocarbon groups, and n is an integer of 1 to 200, with a diol A having a cyclic acetal skeleton in the presence of a titanium compound E to produce an oligomer; and a polymerization step of polymerizing the oligomer to increase a molecular weight.