Abstract: Bicomponent fibers of different cross-sections may be formed without changing the geometry of the spinneret orifices. More specifically, at least two polymers are co-melt-spun through an orifice of fixed geometry so as to achieve a bicomponent fiber having a desired cross-section. In order to change to a bicomponent fiber having a cross-section which is different, therefore, at least one of (1) the differential relative viscosity, (2) the relative proportions of the first and/or second polymers, and (3) the cross-sectional bicomponent distribution of the first and second polymers, is changed. In such a manner, therefore, a wide variety of bicomponent fibers having different cross-sectional geometries may be produced without changing the fixed geometry orifice through which the polymers are co-melt-spun. Thus, bicomponent fiber cross-sections may be "engineered" to suit a variety of needs without necessarily shutting down production equipment in order to change spinnerets.

Abstract: Novel bicomponent fibers have a sheath domain and an core domain which is embedded entirely within, and thereby completely surrounded by, the polyamide domain. The core domain is annular and defines a longitudinally extending central void. The preferred bicomponent fibers have a sheath-core structure wherein the polyamide domain constitutes the sheath and a fiber-forming polyolefin polymer constitutes the core. The preferred trilobal bicomponent fibers will exhibit a modification ratio of between 2 to 4, an arm angle of between 7.degree. to about 35.degree., and a total cross-sectional void area between about 3 and about 10 percent. Each lobe of the fiber may optionally contain a lobal void space which, if present, is preferably radially elongate in cross-section.

Abstract: Multicomponent fibers and methods and apparatus for producing the same are provided such that an inter-domain boundary layer is interposed between distinct domains formed of incompatible polymers so as to minimize (if not eliminate entirely) separation of the domains at their interfacial boundary. The inter-domain boundary layer is formed of a heterogeneous mixture of the polymers forming the respective adjacent domains between which the boundary layer is interposed. The inter-boundary layer will most preferably include rivulets or fingers of each polymer forming the adjacent domains which interlock with one another in a randomly tortuous manner. These different polymer rivulets thereby effectively increase the surface area and mechanical interlocking at the interfacial boundary between the fiber domains thereby increasing the adhesion therebetween.

Abstract: Multicomponent fibers have a primary core, and multiple secondary cores equidistantly radially spaced from one another and from the primary core. The primary and secondary cores are entirely embedded within (and thus completely encased by) a primary sheath. Optionally, the primary sheath may be entirely or partly surrounded by a secondary sheath. The primary and secondary cores may be spun from polymers having distinctly different or complementary properties which are surrounded by a sheath or sheaths formed of another polymer(s) which protects the cores.

Abstract: Bicomponent fibers of different cross-sections may be formed without changing the geometry of the spinneret orifices. More specifically, at least two polymers are co-melt-spun through an orifice of fixed geometry so as to achieve a bicomponent fiber having a desired cross-section. In order to change to a bicomponent fiber having a cross-section which is different, therefore, at least one of (1) the differential relative viscosity, (2) the relative proportions of the first and/or second polymers, and (3) the cross-sectional bicomponent distribution of the first and second polymers, is changed. In such a manner, therefore, a wide variety of bicomponent fibers having different cross-sectional geometries may be produced without changing the fixed geometry orifice through which the polymers are co-melt-spun. Thus, bicomponent fiber cross-sections may be "engineered" to suit a variety of needs without necessarily shutting down production equipment in order to change spinnerets.

Abstract: Multicomponent fibers and methods of producing the same are provided such that an inter-domain boundary layer is interposed between distinct domains formed of incompatible polymers so as to minimize (if not eliminate entirely) separation of the domains at their interfacial boundary. The polymer forming the inter-domain boundary layer therefore is provided so as to be compatible with the otherwise incompatible polymers forming each of the domains between which it is interposed.

Abstract: Relatively thin (e.g., thickness of less than about 2.5 mm, and typically no greater than about 1.0 mm) plates for synthetic fiber-forming spin packs include a first metal layer exhibiting a relatively slow photochemical etching property and a second metal layer exhibiting a relatively fast photochemical etching property which are adhered (laminated) to one another to form a composite substrate structure. The differential etch rates as between the first and second metal layers permit relatively dimensionally larger distribution channels and relatively dimensionally precise through holes to be formed in the composite substrate. In this regard, the second metal layer permits the formation via photochemical etching of dimensionally deeper and/or wider polymer distribution channels. The first metal layer, on the other hand, allows for the formation of relatively dimensionally precise through holes via concurrent (simultaneous) etching with the second metal layer.

Abstract: Multicomponent fiber and a method of producing the same whereby the inter-domain boundary layer between the distinct domains is surface roughened and/or mechanically modified so as to increase the surface area contact (and thereby the adhesion) therebetween. As such, delamination of the domains at their interfacial boundary layer is minimized (if not eliminated entirely). Preferably, the fibers are concentric core-sheath bicomponent fibers whereby the core is surface roughened and/or mechanically modified so that of the inter-domain boundary layer between the core and the sheath appears in cross-section to be serrated, undulated and/or ribbed so as to provide a core domain with a shape factor of between about 25 to about 55.

Abstract: Novel bicomponent fibers have a sheath domain and an core domain which is embedded entirely within, and thereby completely surrounded by, the polyamide domain. The core domain is annular and defines a longitudinally extending central void. The preferred bicomponent fibers have a sheath-core structure wherein the polyamide domain constitutes the sheath and a fiber-forming polyolefin polymer constitutes the core. The preferred trilobal bicomponent fibers will exhibit a modification ratio of between 2 to 4, an arm angle of between 7.degree. to about 35.degree., and a total cross-sectional void area between about 3 and about 10 percent. Each lobe of the fiber may optionally contain a lobal void space which, if present, is preferably radially elongate in cross-section.

Abstract: Colored bicomponent filaments have a particulate colorant dispersed throughout one of the fiber domains while another of the fiber domains is colorant-free. More specifically, the filaments have at least two distinct components arranged longitudinally coextensive with one another. The arrangement of the components may be a sheath/core structure or a side-by-side structure. One of the components contains a colorant and the other one does not (i.e., is colorant free). The colorant-free component is most preferably formed of a polymeric material which is incompatible with the particulate colorant, whereas the colorant-containing component is most preferably formed of a polymeric material which is compatible with the particulate colorant.

Abstract: Multicomponent fibers and methods and apparatus for producing the same are provided such that an inter-domain boundary layer is interposed between distinct domains formed of incompatible polymers so as to minimize (if not eliminate entirely) separation of the domains at their interfacial boundary. The inter-domain boundary layer is formed of a heterogeneous mixture of the polymers forming the respective adjacent domains between which the boundary layer is interposed. The inter-boundary layer will most preferably include rivulets or fingers of each polymer forming the adjacent domains which interlock with one another in a randomly tortuous manner. These different polymer rivulets thereby effectively increase the surface area and mechanical interlocking at the interfacial boundary between the fiber domains thereby increasing the adhesion therebetween.

Abstract: Multicomponent fibers have a primary core, and multiple secondary cores equidistantly radially spaced from one another and from the primary core. The primary and secondary cores are entirely embedded within (and thus completely encased by) a primary sheath. Optionally, the primary sheath may be entirely or partly surrounded by a secondary sheath. The primary and secondary cores may be spun from polymers having distinctly different or complementary properties which are surrounded by a sheath or sheaths formed of another polymer(s) which protects the cores.

Abstract: Synthetic filaments include a nonaqueous additive system having dispersant-coated pigments physically dispersed in a liquid nonaqueous polymeric carrier. The additive system is most preferably in the form of a particulate paste which can be added in metered amounts (dosed) to a melt flow of the polymeric host material prior to being spun into filaments. By providing a number of additive systems having a number of different additive attributes, and controllably dosing one or more into the melt flow of polymeric material, melt-spun filaments having different additive attributes may be produced on a continuous basis (i.e., without shutting down the spinning operation). The filaments may be included in yarns which are formed into carpet structures.

Abstract: Methods of continuously producing sequential lengths of different additive-containing melt-spun filaments include continuously supplying a melt-spinnable polymeric host material to orifices of a spinneret and controllably dosing at least one dispersible additive concentrate system containing a pigment in a liquid nonaqueous polymeric carrier to the melt flow of polymeric host material upstream of the spinneret orifices. In such a manner, a first polymeric mixture of the dispersible additive concentrate system and the polymeric host material is obtained which achieves an additive attribute. During a first time interval, the first mixture is extruded through the spinneret orifices; and thereafter, during a second subsequent time interval, the dosing of the at least one dispersible additive is changed so as to form a second mixture having a second additive attribute different from the first additive attribute while continuously supplying the melt flow of polymeric host material to the spinneret orifices.

Abstract: A method of separating two immiscible, melt-viscosity-differing thermoplastic polymer components from a mixed liquid stream thereof forms two discrete and continuous phases having a sheath/core configuration, wherein the sheath substantially contains the polymer component with the higher melt viscosity and the core substantially contains the polymer component with the lower melt viscosity. The mixed liquid stream contains a predominant amount (i.e., greater than 50% by volume) of the higher viscosity polymer component and a minority amount (i.e., less than 50% by volume) of the lower viscosity polymer component. The method involves directing the stream through a shear zone at a shear temperature and a shear rate sufficient to form the two discrete and continuous phases, the first of which substantially contains the lower viscosity polymer component and the second of which substantially contains the higher viscosity polymer component.

Abstract: Nonaqueous additive systems which includes dispersant-coated pigments physically dispersed in a liquid nonaqueous polymeric carrier are added directly to a melt flow of a polymeric host material prior to spinning. The additive system is most preferably in the form of a particulate paste which can be added in metered amounts (dosed) to a melt flow of the polymeric host material prior to being spun into filaments. By providing a number of additive systems having a number of different additive attributes, and controllably dosing one or more into the melt flow of polymeric material, melt-spun filaments having different additive attributes may be produced on a continuous basis (i.e., without shutting down the spinning operation).