Polyester fibers

A paper making polyester fiber, the improvement comprising that the papermaking polyester fiber comprises a copolymer containing a dicarboxylic acid component and has applied to the surface thereof a copolymerized polyester (I) which consists of (A) a polyester comprising terephthalic acid or an ester-forming derivative of terephthalic acid, isophthalic acid or an ester-forming derivative of isophthalic acid and a lower alkylene glycol (b) about 0.2 mol percent to about 40 mol percent, with respect to the quantity of the dicarboxylic acid component in the copolymer to be produced, of an ester-forming alkali metal sulfonate and (c) about 20 percent by weight to about 90 percent by weight, with respect to the quantity of the copolymer to be produced, of a polyethylene glycol having an average molecular weight within the range of from about 500 to 1200, wherein the paper making polyester fiber has a denier number within the range of from about 0.1 to about 3.0 and a length within the range from about 5 mm to about 25 mm, and provides a packing factor of more than about 40 and a quantity of residual fibers of less than about 1000 mg on a flat screen plate when measured by the flat screen method.