| abstract |
(57) [Summary] [Structure] A phosphinic acid compound and / or a phosphonous acid compound having a low purity when a polyester is produced from a dicarboxylic acid or its ester-forming derivative and a diol or its ester-forming derivative as main starting materials. Is added to the reaction system so as to contain 0.05 to 5% by weight as a phosphorus atom in the obtained polyester, and a germanium compound is used as a polycondensation catalyst. A method for producing a flame-retardant polyester, which comprises using a titanium compound and / or a titanium compound. [Effect] By using a low-purity phosphinic acid compound, it is possible to efficiently produce a flame-retardant polyester having good processability in the polyester molding step. |