Polyester copolymer and method of producing same

Abstract

A polyester copolymer has two types of ester bond-forming monomer residues as main structural units when the two types of ester bond-forming monomers are defined as “monomer A” and “monomer B”, respectively, the polyester copolymer satisfies (1) and (2): (1) an R value represented by equation: R value=[AB]/(2[A][B])×100 [A]: mole fraction of monomer A residues in the polyester copolymer [% by mol], [B]: mole fraction of monomer B residues in the polyester copolymer [% by mol], and [AB]: mole fraction of a structure in which the monomer A residues and the monomer B residues are adjacent to each other (A-B and B-A) in the polyester copolymer [% by mol], is 0.45 or more and 0.99 or less; and (2) a crystallization rate of at least one of the monomer A residues and the monomer B residues is less than 14%.

Dependencies are inferred from the claim text.