| abstract |
Hollow water-absorbing polyester filaments each having a number of fine caves which are evenly distributed in at least a portion of the filament and through which the hollow is connected to the outside of the filament, are produced (1) by preparing hollow filaments from a blend of a principal polyester component and a cave-forming agent consisting of at least one member selected from: (i) copolyesters containing an additional divalent organic sulfonic acid compound moiety of the formula (II): <IMAGE> (II) wherein Z is a trivalent aromatic or aliphatic hydrocarbon radical, M1 is H or metal atom, R1 is an ester-forming organic radical and R2 is an H atom or ester-forming organic radical; (ii) phosphorus compounds of the formula (III): <IMAGE> (III) wherein R3 is a monovalent organic radical, X is -OR4, wherein R4 is an H atom or a monovalent organic radical, -OM3, wherein M3 is a metal atom, or a monovalent organic radical, M2 is a metal atom and m=0 or 1, and; (iii) aromatic carboxy-sulfonic acid compounds of the formula (IV): <IMAGE> (IV) wherein Y is an H atom or ester-forming organic radical, M4 and M5 each are a metal atom, respectively, and n=1 or 2, and (2) by removing the at least a portion of cave-forming agent and a portion of the principal polyester component from the resultant hollow filaments so as to form numerous concaves on the peripheral and hollow surfaces, numerous pores in the body of the filament, and numerous channels through which the pores are connected to each other and to the concaves, the concaves and pores having a longitudinal size of 50 times or less the lateral size thereof, which is 0.01 to 3 microns. |