Polyester monofilament
 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. 
Toray Industries, Inc.
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Y10T Y10T D01F D01F
additional additional inventional inventional
Takehiko Toyohiko Yoshinori
Miyoshi Masuda Horii