Abstract: A polyester composition with a polymer component which contains 99.8-60 wt % of a polyester with a terminal carboxyl group concentration of not more than 10 equivalents/10.sup.6 g (A) and 0.2-40 wt % of a thermoplastic polymer containing no fluorine atoms (B), and which also includes 0.005-1.5 wt % of unreacted carbodiimide compound (C), polyester monofilaments obtained from the composition, an industrial fabric and paper drier canvas which employ the polyester monofilaments, and a rubber mold reinforced with the polyester monofilaments.The composition is obtained by kneading in the polyester either after or during the process of melting and kneading the thermoplastic polymer containing no fluorine atoms and the carbodiimide compound, and the composition is spun, drawn and thermoset to obtain polyester monofilaments.

Abstract: The polyester monofilament of this invention has a terminal carboxyl group concentration of not more than 10 equivalent weights/10.sup.6 g and contains an unaltered carbodiimide compound in an amount in the range of from 0.005 to 1.5% by weight and a fluorine type polymer in an amount in the range of from 0.01 to 30% by weight. The polyester monofilament of this invention has an excellent resistance to hydrolysis and proof against staining. When used under high temperature and high humidity conditions susceptible to hydrolysis and the collection of stains, as when used in a papermaking drier canvas, it brings about a notable effect of prolonging the service life of the canvas and lengthening the cycle of cleaning.