Abstract: A method of extruding polypropylene filaments in which the polypropylene is extruded at a temperature below 375.degree. F., such as in the range 335.degree. F. to 365.degree. F., particularly about 350.degree. F., into a quiescent hot zone having a temperature sufficiently high to retard cooling of the extruded polypropylene filaments. The filaments are then passed through and cooled in a quench zone across which cooling air is blown. The polypropylene has a narrow molecular weight distribution with a swell value less than 2.5, and its melt flow may be greater than 30. The yarn is drawn-down in the hot zone and the filaments may be drawn-down to an undrawn denier of less than 15 with substantial elimination of resonance.

Abstract: An extruder screw for extruding solution dyed polypropylene at low temperatures, for example, in the range 335.degree. F. to 365.degree. F., has feed, transition and metering sections, the length of the transition section being at least equal to the sum of the lengths of the feed and metering sections. The transition section has a compression ratio of at least 4.5:1 to create substantial backflow of the melt therein to thoroughly mix the melt. The transition section may be a continuous compression zone or have two compression portions connected by a dwell portion.

Abstract: A method of melt spinning solution dyed polypropylene filaments, with quicker color changes, comprises passing solution dyed polypropylene melt of a first color at a temperature below 400.degree. F., particularly in the range 350.degree. F. to 360.degree. F., through a plurality of shallow horizontally disposed cavities in a spin pack. Each cavity contains a set of horizontally disposed mesh screens which occupies at least one-third of the depth thereof, the melt passing through all of the sets of mesh screens and occupying only a low internal volume in the spin pack as it passes therethrough and is extruded therefrom. Then, when it is needed to change color, natural polypropylene melt is passed through the spin pack and natural filaments extruded. Thereafter, solution dyed melt of a second color is passed through the spin pack and filaments of the second color extruded, the color change from the first color to the second color being effected quickly and completely by purging through the spin pack.

Abstract: A method of extruding multi-filament polypropylene yarn in which the polypropylene is extruded at a temperature below 425.degree. F., such as in the range 415.degree. F. to 350.degree. F., particularly about 400.degree. F., into a hot zone having a temperature sufficiently high to retard cooling of the extruded polypropylene yarn. The temperature of the hot zone can be within 60.degree. F. of the temperature of extrusion. The yarn is then passed through a quenching zone across which air is blown to cool the yarn. The swell value of the polypropylene can be less than 3 and its melt flow may be greater than 30. The yarn is drawn down in the hot zone and the filaments may be drawn down to an undrawn denier of less than 40.

Abstract: Air quench extrusion apparatus and method are described for extruding yarn from polyolefin material. The yarn is first extruded downwards into a hot zone surrounded by a shroud, and then passes through a quenching zone across which cooling air, or gas, is moved to cool the yarn. Immediately adjacent the lower end of the quenching zone is disposed a denier control roll for pulling the yarn out of the quenching zone at a controlled rate causing the yarn to be drawn down in denier in the hot zone. The hot zone is small in volume relative to the quenching zone and contains quiescent air at a temperature close to that at which the material is extruded. The height of the apparatus from extrusion to the denier control roll is less than 10 feet, allowing the apparatus to be located in a single story building. At least two multi-filament yarns are simultaneously extruded into the hot zone which is rectangular in cross-section.

Abstract: A method of extruding multi-filament polypropylene yarn in which the polypropylene is extruded at a temperature below 425.degree. F., such as in the range 415.degree. F. to 350.degree. F., particularly about 400.degree. F., into a hot zone having a temperature sufficiently high to retard cooling of the extruded polypropylene yarn. The temperature of the hot zone can be within 60.degree. F. of the temperature of extrusion. The yarn is then passed through a quenching zone across which air is blown to cool the yarn. The swell value of the polypropylene can be less than 3 and its melt flow may be greater than 30. The yarn is drawn down in the hot zone and the filaments may be drawn down to an undrawn denier of less than 40.

Abstract: Apparatus and method are described for extruding filaments of thermoplastic material, particularly polypropylene, by liquid quench melt spinning in which a baffle arrangement is disposed in the quench liquid around the location where the filaments enter to reduce turbulence, vortexing, and liquid level variation. The baffle arrangement forms an opentopped box-like structure with two quench liquid inlet apertures and one quench liquid outlet aperture. Yarn guides are disposed inside this structure and the filaments, after solidifying, pass around the yarn guides and then upwards, at an angle of about 30 degrees to the horizontal, through the quench liquid outlet aperture. The passage of the filaments creates a pumping action of the quench liquid in through the two inlet apertures and out through the outlet aperture. The area of the outlet aperture is less than the sum of the areas of the inlet apertures, to create an inefficient pump.

Abstract: Apparatus and method for stuffer box crimping yarn is disclosed in which continuous filament yarn having a thermoplastic component and varying in denier along its length is substantially uniformly drawn and then treated in the same crimping area and where that portion of the yarn of higher denier is texturized to a lesser extent than that portion of the yarn of lower denier. The apparatus for carrying out the method provides a crimp site and a very short plug guiding area which establishes the lateral width of the plug. A pair of pressure shoes are oppositely disposed on either side of the plug of crimped yarn as it leaves the guiding area.

Abstract: Apparatus for compression crimping fibrous material, such as synthetic continuous filament yarn, is provided comprising means defining a compression crimping zone, means for feeding fibrous material into the compression crimping zone and a pair of movable members each having a face substantially opposed to a face of the other, said faces defining lateral walls of the zone and being biased toward each other to restrict egress of the fibrous material from the zone and thereby exert a back pressure on the fibrous material, causing the fibrous material to buckle, form a plug in the zone and thereby crimp in the zone, the aforementioned face of each of the members being laterally restricted by means rigidly connected to the member whereby the plug is prevented from escaping laterally from between the substantially opposed faces of the members.

Abstract: In apparatus for compression crimping fibrous material, such as yarn, comprising a chamber for receiving the yarn from a pair of feed rollers and in which chamber the yarn is compressed, the chamber having corners intercepted by the periphery of the rollers adjacent the sides; there are provided guiding ramps adjacent the nip of the rollers to keep the yarn away from the corners as the yarn advances from the rollers into the chamber.

Abstract: Apparatus and method for stuffer box crimping yarn is disclosed in which continuous filament drawn yarn having a thermoplastic component and varying in denier along its length is treated in the same crimping area and where that portion of the yarn of higher denier is texturized to a lesser extent than that portion of the yarn of lower denier. The apparatus for carrying out the method provides a crimp site and a very short plug guiding area which establishes the lateral width of the plug. A pair of pressure shoes are oppositely disposed on either side of the plug of crimped yarn as it leaves the guiding area.