Abstract: A filament for artificial hair is excellent in terms of volume and luster and not subject to yarn cracking or yarn breakage. The filament is a filament of a thermoplastic resin, its shape of a cross section in a direction perpendicular to a fiber axis is a multilobal shape having three or more interlobe gap regions, widths W2 of the interlobe gap regions are 10 to 60% of a width W1 of the filament, and depths H2 of the interlobe gap regions are 5 to 30% of a height H1 of the filament.

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 present invention relates to a toothbrush (a) wherein a filament implant part is non easily contaminated with bacteria even when using for a long period of time. The toothbrush is characterized by implanting of a filament coveted by a coat of a complex of a polymer having cation exchange capacity and a cationic bactericide.