Polyester conjugate filament thick-fine yarn fabric and method for production thereof

A process for producing a polyester conjugate filament thick-and-thin yarn fabric comprising:

• separately melting a polyester resin having an intrinsic viscosity of 0.3 to 0.9, determined in orthochlorophenol at 30° C., and an other polyester resin having an intrinsic viscosity of 0.1 to 0.5 above the intrinsic viscosity of the former polyester resin;
• extruding the melts of the two types of the polyester resins through a side-by-side type conjugate multifilament-forming spinneret or an eccentric core-in-sheath type conjugate multifilament-forming spinneret, to form conjugate multifilaments;
• winding up the resultant side-by-side type undrawn conjugate multifilament yarn or eccentric core-in-sheath type undrawn conjugate multifilament yarn at a speed of 1,000 to 4,500 m/minute;
• while unwinding the wound undrawn conjugate multifilament yarn, unevenly drawing the unwound undrawn conjugate multifilament yarn in the filament axis direction at a draw ratio lower than the natural draw ratio of the undrawn multifilament yarn represented by a lowest draw ratio in a draw ratio range in which the undrawn multifilament yarn can be drawn at room temperature without necking of the filaments, to produce a drawn thick-and-thin yarn comprising a plurality of drawn thick-and-thin conjugate filaments each having a plurality of thick portions and a plurality of thin portions arranged alternately with each other and having uneven lengths, respectively, while the unevenly drawing procedure is controlled so that when the resultant drawn thick-and-thin yarn is observed by an electron microscope, an apparent thick-to-thin ratio represented by a ratio of a largest thickness to a smallest thickness of the yarn in a region in a length of 10 cm of the yarn, is 1.05 or more;
• producing a fabric comprising the drawn conjugate multifilament thick-and-thin yarn;
• and
• subjecting the fabric to a mass-reduction treatment with an alkali at a mass-reduction of 3% or more but not more than 30%, to thereby cause a plurality of cracks to be formed in the peripheral surfaces of the individual conjugate polyester filaments in a direction intersecting the axes of the individual conjugate polyester filaments.