Patent ID: 8168727

Claim:
A polyester resin comprising a recurring unit (A) represented by the following formula and a recurring unit (B) represented by the following formula as the main constituents: —O—C(O)—R 1 —C(O)—O—R 2 —O— (A) —O—C(O)—R 3 —C(O)—O—R 2 —O— (B) {in the above formulas, R 1 is a phenylene group or naphthalenediyl group, R 2 is an alkylene group having 2 to 4 carbon atoms or cyclohexanedimethylene group, and R 3 is a group represented by the following formula (C): (in the above formula, R 4 is an alkylene group having 2 to 10 carbon atoms)} wherein the content of the recurring unit (B) is not less than 5 mol % and less than 50 mol % based on the total number of moles of the recurring unit (A) and the recurring unit (B), the content of the recurring unit (A) and the recurring unit (B) is 90 to 100 mol % based on the total number of all recurring units of the polyester resin, and the recurring units (A) and (B) satisfy the following expression (1): ( C A-B )/2( C A )×( C B )<0.90 (1) (in the above expression, (C A ) is the molar fraction of the recurring unit (A) in the polyester resin based on the total number of moles of the recurring units (A) and (B), (C B ) is the molar fraction of the recurring unit (B) in the polyester resin based on the total number of moles of the recurring units (A) and (B), and (C A-B ) is the ratio of adjacent recurring units (A) and (B) based on the total number of adjacent recurring units (A) and (A), adjacent recurring units (B) and (B), and adjacent recurring units (A) and (B)).