Abstract: Flat continuous multifilament nylon apparel yarns suitable for critical dye applications and a process for making such yarns. The process for making the yarns includes spinning nylon polymer with a relative viscosity between about 35 and about 80 and stabilizing to make a feed yarn. The withdrawal speed in spinning is sufficiently high that highly uniform feed yarns are provided. In the process, feed yarn is drawn and subsequently relaxed, preferably in the form of a warp of yarns, so that the resulting drawn yarns have properties suitable for use as flat yarns and have excellent dye uniformity with large molecule acid dyes.

Abstract: Incorporating a minor amount of a hydrogen bonding additive such as nylon 6 monomer or 2-methyl-pentamethylene adipamide monomer in a nylon 66 high RV polymer for making nylon 66 POY provides unexpected downstream advantages over homopolymer nylon 66 POY, especially in draw-texturing to make bulky yarns for use in hosiery.

Abstract: Drawing, especially cold-drawing, or hot-drawing or other heat-treatments of spin-oriented crystalline polyester filaments, and particularly polyester feed yarns, that have been prepared by spinning at speeds of, e.g., 4 km/min, and have low shrinkage and no natural draw ratio in the conventional sense, provides useful technique for obtaining uniform drawn filaments of desired denier and thereby provides improved flexibility to obtain filaments and yarns of various sub-deniers.

Abstract: Incorporating a minor amount of a hydrogen bonding additive such as nylon 6 monomer or 2-methyl-pentamethylene adipamide monomer in a nylon 66 high RV polymer for making nylon 66 POY provides unexpected downstream advantages over homopolymer nylon 66 POY, especially in draw-texturing to make bulky yarns for use in hosiery.

Abstract: Drawing, especially cold-drawing, or hot-drawing or other heat-treatments of spin-oriented crystalline polyester filaments, and particularly polyester feed yarns, that have been prepared by spinning at speeds of, e.g., 4 kg/min, and have low shrinkage and no natural draw ratio in the conventional sense, provides useful technique for obtaining uniform drawn filaments of desired denier and thereby provides improved flexibility to obtain filaments and yarns of various denier. The resulting uniform filaments have useful properties that are improved in certain respects.

Abstract: Poly(ethylene terephthalate) filaments of enhanced dyeability, low boil-off shrinkage (even in as-spun condition), good thermal stability over a large temperature range; and useful as texturing feed yarns and/or as hard yarns requiring no further drawing are prepared by spinning at extremely high speeds, and are characterized by a long period spacing above 300 A in their as-spun condition, and, whether in as-spun condition or after heat-treatment, by a low skin-core value as measured by a differential birefringence in relation to their stress measured at 20% extension (which correlates approximately with the spinning speed), a large crystal size, and low amorphous orientation. The continuous filament yarns may be draw-textured to provide textured yarns which also show enhanced dyeability. The staple fiber yarns also have very useful properties as compared with conventional staple yarns.

Abstract: New poly(ethylene terephthalate) flat yarns and tows having physical properties and dyeability more akin to cellulose acetate than to conventional poly(ethylene terephthalate) flat yarns are prepared directly by spinning at speeds of about 4000 meters/minute. Among the useful physical properties are a modulus of 30 to 65, which is relatively unaffected by boiling, low boil-off shrinkage, no need for heat setting, low shrinkage tension, large crystal size, and low amorphous orientation which is measured by a value termed "amorphous modulus." The flat yarns may be used, e.g. in textile fabrics, without drawing, and may be modified, e.g. by air-jet texturing. The tows may be converted into staple fiber.

Abstract: Poly(ethylene terephthalate) filaments of enhanced dyeability, low boil-off shrinkage (even in as-spun condition), good thermal stability over a large temperature range, and useful as texturing feed yarns and/or as hard yarns requiring no further drawing are prepared by spinning at extremely high speeds, and are characterized by a long period spacing above 300 A in their as-spun condition, and, whether in as-spun condition or after heat-treatment, by a low skin-core value as measured by a differential birefringence in relation to their stress measured at 20% extension (which correlates approximately with the spinning speed), a large crystal size, and low amorphous orientation. The continuous filament yarns may be draw-textured to provide textured yarns which also show enhanced dyeability. The staple fiber yarns also have very useful properties as compared with conventional staple yarns.