A MANUFACTURING METHOD OF FLAME RETARDANT POLYESTER RESIN

A method for preparing a flame resistant polyester resin is provided to obtain a polyester resin having excellent flame resistant while maintaining other physical properties, such as tensile strength and impact strength. The method for preparing a flame resistant polyester resin comprises the steps of: mixing a flame retardant represented by the following chemical formula 1 with an alkyl dicarboxylate and a diol to perform esterification or transesterification; and adding a flame retardant represented by the following chemical formula 2 and a polycondensation catalyst to the product obtained from the preceding step to perform polycondensation and to obtain a flame resistant polyester master batch. In chemical formula 1, each of R1 and R2 independently represents a C1-C15 alkyl, aryl or alkylaryl. In chemical formula 2, R3 is a C1-C15 alkyl, aryl or alkylaryl. In the method, the flame retardant represented by chemical formula 1 is used in an amount of 0.1-40 wt% based on the total weight of the esterification or transterification mixture, and the flame retardant represented by chemical formula 2 is used in an amount of 0.001-20 wt% based on the total weight of the resin composition.