Abstract: Shaped articles, such as fibers, formed of a polyamide formed by salt-blending the polyamide precursor salt with a cationic dye modifier, such as the dimethyl ester of 5-sulfoisophthalic acid, followed by polymerization, are rendered resistant to staining by acid dyes at ambient conditions either by adding an acid dye to the polymer melt or by dyeing with an acid dye from an acid dyebath at pH 2 to 7 and 60.degree. to 100.degree. C. so that the shaped article contains from at least 0.0048 and preferably at least 0.0096 wt % of an acid dyestuff. In a preferred aspect of the invention, the shaped articles are oriented, crimped, heat-set fibers for use as the facing in carpets.

Abstract: Bulked random copolyamide yarns having enhanced dyeability as compared to comparable nylon 6 fibers are disclosed. The random copolyamides contain from 80 to 96% by weight of nylon 6 units and 4 to 20% by weight of nylon 6,6 units with from 90 to 94% nylon 6 and 6 to 10% nylon 6,6 being the preferred range. Further increases in dyeability are obtained by steam heat-setting the yarns.

Abstract: A fiber having a reduced dye rate compared to nylon 6 formed from a block copolymer of 2-30 wt % nylon 6,6 and 70-98 wt % nylon 6 which fiber has a stain resist applied thereto.

Abstract: Blends of nylon 6,6, nylon 6 or nylon 6,6/6 copolymer which contain a randomly copolymerized cationic dye modifier are formed by melt blending such copolymer with a polyamide, having 8 to 22 carbon atoms per amide link to form a block copolymer composition which is resistant to staining with acid dyes under ambient temperature and pH conditions.

Abstract: High twist fibers are produced in a spin/quench/twist process directly from a modified spinneret. The spinneret consists of capillaries that are installed in highly elongated inserts which are surrounded by heat deflecting shields surrounded by an annular concentric orifice supplied with a fluid (air or steam preferred) that simultaneously quenches and twists the emerging filaments as they exit the capillary quench/torque jet.

Abstract: Shaped articles, such as fibers, formed of a polyamide formed by salt-blending the polyamide precursor salt with a cationic dye modifier, such as the dimethyl ester of 5-sulfoisophthalic acid, followed by polymerization, are rendered resistant to staining by acid dyes at ambient conditions either by adding an acid dye to the polymer melt or by dyeing with an acid dye from an acid dyebath at pH 2 to 7 and 60.degree. to 100.degree. C. so that the shaped article contains from at least 0.0048 and preferably at least 0.0096 wt % of an acid dyestuff. In a preferred aspect of the invention, the shaped articles are oriented, crimped, heat-set fibers for use as the facing in carpets.

Abstract: Blends of nylon 6,6, nylon 6 or nylon 6,6/6 copolymer which contain a randomly copolymerized cationic dye modifier are formed by melt blending such copolymer with a polyamide having 8 to 22 carbon atoms per amide link to form a block copolymer composition which is resistant to staining with acid dyes under ambient temperature and pH conditions.

Abstract: Process for producing producer-colored nylon fibers which are stain-resistant to acid dyes are made by adding pigment to nylon copolymers containing 0.25-4.0 percent by weight of an aromatic sulfonate or an alkali metal salt thereof.

Abstract: A process for preparing a nylon 66/6 copolymer fiber with reduced spherulites comprising adding 1-6% caprolactam and 0.001-2% water-soluble inorganic calcium salt to 94-99% nylon 66 salt to form a nylon 66/6 salt solution, polymerizing the salt solution to form a polymer, and extruding the polymer.

Abstract: A process for making a polyhexamethylene adipamide fiber with a spherulite rating of 1 in which a molten polymer of polyhexamethylene adipamide is injected with fluorocarbon and subjected to low shear.

Abstract: A crimped fiber having a plurality of cells and bends characterized by the total area occupied by the cells within a cross-section of the fiber at the bends being less than 50% of the area occupied by the cells within a cross-section of the fiber at other than the bends.

Abstract: A room temperature dyeable polyamide fiber with low spherulites containing 1-6% nylon 6, 94-99% nylon 66 and 0.001-2% of a highly reactive metal, preferably calcium and the process for making the fiber are disclosed.

Abstract: A fiber having 1/2-50% substantially gas-filled and essentially all closed cells having a diameter of 0.2-25 microns and a length to diameter ratio of greater than 500 is disclosed. The fiber is made by mixing a fluorocarbon blowing agent into molten polymer, shearing the polymer at a high shear rate, extruding the polymer in a spinneret capillary at a low jet velocity and a low capillary entrance pressure and drawing down the polymer at a total extension greater than 1000.

Abstract: A method of providing automatic positional control spinning pump throughput on a multiposition spinning machine during periods of yarn interruption by sensing yarn breaks and reducing spinning pump speed by a predetermined amount.

Abstract: The dyeability of carpet yarns prepared from random copolymers of nylon 66 and 6-12 wt. % nylon 6 is improved by subjecting the yarn to saturated steam at temperatures close to the melting point of the copolymer. The copolymers used in the invention have an amine end content of 30-80 gram equivalents per 1000 kilograms of polymer and a relative viscosity of 55-85 in filament form.

Abstract: An improved method for making a continuous filament heather dyeable yarn involves cobulking in a hot fluid jet process a first unbulked yarn with a second differentially dyeable previously bulked yarn. The method enhances differential dyeability in the product when both yarns have a common type of chemical dye site and the second yarn has a greater concentration of those dye sites than the first yarn.