Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Rod – strand – filament or fiber
Reexamination Certificate
2000-03-01
2001-04-24
Edwards, N. (Department: 1774)
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Rod, strand, filament or fiber
C428S364000, C428S370000
Reexamination Certificate
active
06221491
ABSTRACT:
BACKGROUND OF THE INVENTION
The shape of a textile filament can impart very specialized properties to a multi-filament strand. For example, a multi-filament strand constructed from a plurality of filaments having various polygonal cross-sections has deer-skin or suede-like properties. Further, a multi-lobed filament with the distal ends slightly curved in a uniform direction has resilience or resistance to matting. Thus, the properties imparted by a given textile filament shape may be quite distinctive.
Conventional multi-filament articles such as yarns, tows, threads, twines and ropes are made from filaments having essentially round cross-sections. These articles have voids between the filaments due to the essentially round filament cross-sections. It is an object of the present invention to create a novel synthetic filament having a cross-section such that, when combined with other like filaments, it creates a more densely packed multi-filament article in cross-section. The resulting multi-filament article will have a smaller diameter but retain the tensile strength equivalent to the conventional multi-filament article having a larger diameter but essentially the same multi-filament cross-sectional area.
Another object of the present invention is to provide a multi-filament article with improved distribution of tension such that the multi-filament article experiences lower stress when flexed as compared to a multi-filament article comprised of conventional round filaments, the two articles having essentially equivalent filament cross-sectional areas. This improved distribution of tension with concomitant lower flexure stress provides a multi-filament article characterized by longer useful life due to its combined flexure and abrasion resistance.
It is a further object of the present invention to provide a spinneret and die/orifice that can form a filament that is substantially hexagonal in cross-section. Such a filament has six longitudinal, substantially planar faces (or facets) capable of abutting the substantially planar faces (or facets) of six other like filaments across essentially each entire face for the entire length of the filaments.
SUMMARY OF THE INVENTION
The present invention relates to filament having a space-filling cross-sectional area and to the multi-filament articles made therefrom. More particularly, the invention relates to filament that is substantially hexagonal in cross-section and to multi-filament articles made from same and characterized by improved properties. The filaments of the present invention can be formed into multi-filament yarns, tows, threads, twines and ropes with increased tensile strength per unit cross-sectional area compared to conventional multi-filament articles formed from round filaments. Since the filaments have a space-filling cross-section in the aggregate, the multi-filament article has a more compact cross-sectional area; as a consequence the article is thinner than conventional prior art multi-filament articles.
Accordingly, the present invention includes a multi-filament article comprising a plurality of filaments formed from filament-forming material, arranged to extend longitudinally. The filaments are formed with a generally hexagonal cross-section having substantially planar faces (or facets) extending along the longitudinal axis, where the filaments are arranged with adjacent filaments having adjacent faces (or facets) in abutment with one another substantially along the length of the multi-filament article. In the context of this invention the term “substantially planar faces or facets” may include some concavity or some convexity of the faces/facets so long as the depth of a circular segment defining the concavity or convexity, in proportion to a side of the hexagon, is less than about 0.06 (6%).
Further, the present invention includes methods for producing a multi-filament article, said multi-filament article being formed from a plurality of generally longitudinally-aligned filaments, each said filament being formed with a generally hexagonal cross-section along its length. A first method comprises the steps of forming a melt of a filament-forming material; placing the melt in communication with a spinneret, said spinneret defining multiple orifices (or dies) wherein each orifice has a centrally disposed, generally circular, center cavity portion, with six side cavity portions projecting radially away from said center cavity portion; extruding said melt through said orifices of said spinneret to form a multi-filament melt stream; and cooling to solidify said multi-filament melt stream to form a multi-filament yarn, each filament of said yarn having a generally hexagonal cross-sectional area and six substantially planar faces/facets extending longitudinally along said filament.
A second method for producing a multi-filament article comprises the steps of forming a solution of a filament-forming material; placing the solution in communication with a spinneret, said spinneret defining multiple orifices (or dies) wherein each orifice has a centrally disposed generally circular center cavity portion, with six side cavity portions projecting radially away from said center cavity portion; extruding said solution through said orifices of said spinneret to form a multi-filament solution stream; solidifying, washing, and drying said multi-filament solution stream to form a multi-filament yarn, each filament of said yarn having a generally hexagonal cross-sectional area and six substantially planar faces or facets extending longitudinally along said filament.
The present invention also includes a novel orifice or die geometry in a spinneret comprising a centrally disposed generally circular center cavity portion, with six side cavity portions projecting radially away from said center cavity portion wherein the six side cavities have ends and wherein at least a portion of the ends are a constant width.
The present invention includes as the filament-forming material any suitable polymeric material, including without limitation the polyamides, polyaramides, polybenzazoles, polycarbonamides, polyolefins, polyethers, polyketones, vinyl polymers, polyesters, and co-polymers and blends of the aforementioned.
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J. Text. Inst., Yarn-on-Yarn Abrasion Testing of Rope Yarns, Part I: The Test Method, 1988, No. 3, pp. 417-431.
Kavesh Sheldon
Lobovsky Alexander
Andrews Virginia S.
Brown Melanie L.
Criss Roger H.
Edwards N.
Honeywell International , Inc.
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