Process for making hydrophilic polyester fiber

Abstract

A new and useful hydrophilic polyester fiber and process of making same are disclosed; the fiber has a stable pore system exhibiting a moisture pickup (regain) of at least about 2 percent by weight at 40.degree. C. and a relative humidity of 92%. Our experiments indicate that the proportion of moisture regain is attributable to capillary condensation in an amount of at least 25%. The hydrophilic properties are the result of a certain pore system within the fiber which enables capilliary condensation to occur significantly. The invention describes one way to accomplish this, namely by the addition of a predetermined amount of a suitable oxalato-complex to a suitable polyester mass. Most preferably, about 10% by weight K.sub.3 Al(C.sub.2 O.sub.4).sub.3 is added to the polyester mass. The fibers are produced by extruding a suitable polyester mass containing 1 to 20 percent by weight of a suitable oxalato complex to form a filament, drawing the filament, and hydrosetting the drawn filament at a suitable temperature, generally between about 90.degree. C. and about 170.degree. C., preferably between about 120.degree. C. and about 140.degree. C., under pressure, and in the presence of liquid water. The hydrophilic polyester produced by the novel process has the favorable moisture regain and many of the favorable texture qualities of cotton, together with the quick drying qualities of conventional polyester fiber.