| abstract |
[PROBLEMS] To provide low birefringence, excellent transparency, mechanical strength and dimensional stability, large refractive index, small Abbe number, high heat resistance, good fluidity, and severe under high temperature and high humidity. Disclosed is a resin that can be suitably used for optical materials and optical components, which does not cause discoloration or dust even under an environment. In a polyester polymer comprising a dicarboxylic acid compound and a dihydroxy compound, the dicarboxylic acid is mainly naphthalenedicarboxylic acid and / or an ester-forming derivative thereof, contains a fluorene-based dihydroxy compound, and has an Abbe number of d line of 23 or less. A polyester resin composition having a glass transition temperature of 130 ° C. or higher and containing at least one phosphoric acid compound and / or phosphorous acid compound. [Selection figure] None |