Yarns comprised of bulked continuous filaments of poly (trimethylene terephthalate)

#This invention relates to the process for manufacturing bulked continuous filaments of poly(trimethylene terephthalate), to the resulting filaments and to carpets made from the bulked filaments

#Carpets which are resistant to staining by common food dyes are currently in high demand. In order to be stain-resistant, nylon carpets must either be treated with a stain-resist chemical or the nylon fibers must have a stain-resist agent incorporated within the polymer.

#However, carpets made from polyester fibers have the benefit of the natural stain-resistant properties of polyester. Polyester carpets are commonly made from filaments of poly(ethylene terephthalate). These carpets may have poor crush resistance (also called pile height retention) and poor texture retention (i.e., the yarns in the tuft tips unravel with wear). Carpets may develop a matted appearance in areas of high foot traffic.

#FIG. 1 is a schematic diagram of an embodiment of this invention wherein a heated feed roll is used to raise the temperature of the filaments above the glass transition temperature prior to drawing.

#FIG. 2 is a schematic diagram of an embodiment of this invention wherein a steam draw assist jet is used to preheat the filaments prior to drawing.

#FIG. 1 illustrates a method for manufacturing bulked continuous filaments of poly(trimethylene terephthalate). Poly(trimethylene terephthalate) polymer having an intrinsic viscosity of 0.6 to 1.3, preferably 0.8 to 1.1 and a water content less than about 100 ppm is extruded at a temperature between 245° to 285° C. through spinneret 10 to form filaments 12 which are pulled by feed roll 14 through quench chimney 16 where the filaments are cooled by a radial flow or cross flow of gas, typically humidified air at a temperature between 10° to 30° C. and at a velocity between 0.2-0.8 m/sec. Prior to feed rolls 14, a spin finish is applied to the filaments by finish applicator 18.

#It is critical that the filaments be at a temperature above their glass transition temperature (Tg) and below 200° C. prior to drawing. Non-uniform drawing and yarn breakage results when drawing below the Tg. Above 200°. is too close to the yarn melting point to effectively orient the molecules. The glass transition temperature of poly(trimethylene terephthalate) filaments varies between about 35°-50° depending upon the moisture content of the filaments, the exact polymer composition and processing conditions such as quenching. In the process shown in FIG. 1, feed rolls 14 may be heated to a temperature between the glass transition temperature and 200° C. in order to heat the filaments for drawing. In an alternate embodiment, feed rolls 14 may be at room temperature and a heated draw pin (not shown), located between the feed rolls and draw rolls 22 may be used to heat the filaments to a temperature between the filament glass transition temperature and 200° C. prior to drawing.

#A preferred embodiment is shown in FIG. 2 where a hot fluid draw assist jet 32 is used to heat the filaments to a temperature between their glass transition temperature and 200° C. The hot fluid may be air or steam. When a steam jet is used, a large amount of finish is removed from the filaments and it is necessary to apply a post draw finish with applicator 34.