Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Rod – strand – filament or fiber
Reexamination Certificate
2000-07-25
2002-07-02
Edwards, N (Department: 1774)
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Rod, strand, filament or fiber
Reexamination Certificate
active
06413635
ABSTRACT:
BACKGROUND OF THE INVENTION
Historically, the textiles industry has increasingly utilized textile yarns which can provide useful levels of stretch and recovery in final fabric or garment form. This trend has been evident over the past 50 years from the advent and use of texturing processes to make polyester yarns for stretch woven fabrics, texturing processes to make stretch nylon yarns for a variety of high stretch knitted fabrics and by the utilization of technology for polymer compositions such as the segmented polyurethanes used to make fibers with inherently high stretch and recovery characteristics.
The approaches to increased stretch and recovery in textile yarns can be categorized in several different ways including categorization via the three technological approaches of 1) texturing processes, 2) compositions, and 3) engineered fibers.
Major examples in category 1 include the technology of single heater friction false twist texturing processes to make polyester yarns for use in stretch woven fabrics. Also included in category 1 are different texturing processes (including friction false twist texturing) to make continuous filament nylon yarns which are used in many applications such as the stretch component in men's socks, in stretch fabrics such as ski wear and in ladies' stretch hosiery.
In category 2 of fiber compositions are those such as fibers and yarns made from the elastomeric segmented polyurethanes which, when utilized in fiber form, are referred to as spandex fibers and yarns.
In category 3, engineered fibers, are several different yarns and technologies for making them. Among the more useful are bicomponent fiber technologies. Such fibers have been known for many years and can be made over a composition range having a wide range of stretch and recovery characteristics. Technology for manufacturing a nylon
ylon bicomponent fiber with a relatively low range of stretch and recovery, useful for stretch hosiery, is described in U.S. Pat. No. 3,399,108. Similar bicomponent yarns for stretch hosiery are also described in U.S. Pat. No. 3,901,989.
A significantly higher range of stretch and recovery suitable for support hosiery is achieved in side by side bicomponent spinning of nylon polymer with a polyurethane polymer described in publications “Monvelle: New Yarn for Support Hosiery”, Knitting Times, Nov. 5, 1973, and in “Biconstituent Fibers from Segmented Polyurethanes and Nylon 6”, J. of Appl. Polym. Sci., v 19, pp 1387-1401, 1975, and in U.S. Pat. No. 3 4,106,313.
The bicomponent fibers in category 3 derive their properties from the dissimilar properties of the side by side components. One such combination is nylon and polyurethane. The optimal retraction of both components is usually actuated by a treatment process which is often a heating step such as steaming or a scouring step or a dyeing step in the fabric or garment finishing process. In the actuation (also called bulking), step such fibers develop a helical crimp due to the difference in retraction of the two components. This effect is often described as following the model of bimetal thermostats and is well known in the art and described in many publications such as “Mechanical Principles of Natural Crimp of Fiber”, R. Brand and S. Backer, Textile Research Journal, pp. 39-51, 1962.
In many applications, additional demands are made upon yarns to provide, in addition to high levels of stretch and recovery, relatively high force levels as the yarn retracts from extension. This high retraction force translates to a force exerted by the fabric or garment made with such yarns. Such requirements are, for example, illustrated by the requirement of such yarns in ladies support hosiery in which it is highly desirable that the garment exert a useful level of force (compression) upon the wearer's leg.
A corollary need is that the garment not exert an excessive level of compression at any point in the garment such as the ankle, the knee, the calf, etc. This corollary need translates to a requirement that the yarn used have a high level of extension within a useful level of stress. Most of the applications requiring such high levels of both stretch and force utilize elastic fibers such as spandex (or spandex wrapped with other fibers such as nylon) or alternatively elastic bicomponent fibers such as those made with nylon and polyurethane as described in the references noted above.
Among the most useful fiber compositions for applications requiring high stretch and recovery (such as in ladies' stretch hosiery) are the nylon fibers. Nylon fibers have several advantages over spandex fibers and over the nylon/polyurethane bicomponent fibers. Nylon fibers are more resistant to degradation by heat or by light or by exposure to bleaches such as common household bleaches containing chlorine. The nylon polymers for fiber spinning are also, in general, less costly than the polyurethanes for spandex fibers or the polyurethanes for nylon/polyurethane bicomponent fibers.
However, it has heretofore not been possible with yarns made from nylon polymers alone to achieve the high stretch and recovery in combination with high retraction force characteristic of the wrapped spandex fibers or the nylon/polyurethane bicomponent fibers. This invention describes such fibers and yarns and methods to make them.
SUMMARY OF THE INVENTION
The present invention relates to a nylon bicomponent yarn comprising one low shrinkage nylon component comprising a homopolymer or a copolymer of isomorphic monomers and one high shrinkage nylon component comprising a random copolyamide comprising at least two mutually non-isomorphic comonomer units, wherein the yarn comprises a Stress Elongation Factor of at least about 4.5 (g/den)(%).
The present invention also regards a process of manufacturing a nylon bicomponent yarn by providing a low shrinkage nylon polymer, the low shrinkage nylon polymer comprising a homopolymer or copolymer of isomorphic monomers; providing a high shrinkage nylon component, the high shrinkage nylon polymer comprising a random copolyamide containing at least two mutually non-isomorphic comonomer units; and, spinning the low shrinkage nylon component and the high shrinkage nylon component to form a yarn with the components being arranged in a side by side configuration , the yarn comprising a Stress Elongation Factor of at least about 4.5 (g/den)(%).
DETAILED DESCRIPTION OF THE INVENTION
As used herein, copolymer percentages are weight percent in the monomer charged to the polymerization process.
As used herein, the term “yarn” comprises one or more filaments whether continuous or staple fibers.
As used herein, the term “textile material” is any knitted, woven, pressed, non woven, or otherwise formed material made from yarn of the present invention, with or without natural or synthetic fibers or mixtures or blends thereof.
As used herein, the term “comonomer” and “comonomer units” means a monomer present at a level of at least about 4% by weight of the component monomer charge.
As used herein, the term “crystalline” means the polymer exhibits regions of three dimensional order as interpreted by various means such as by x-ray diffraction, differential scanning calorimetry, density, and other methods known to the art.
As used herein, the term “isomorphic comonomers” is used as is customary in the industry, that is, comonomers that are capable of replacing each other in crystals without disrupting the crystal structure. Typically, the melting point of a composition of isomorphic comonomers will vary monotonically with no minimum over the composition range. For a more complete discussion of isomorphic comonomers, see, for example, Billmeyer, Textbook of Polymer Science, 3rd edition (1984), page 336.
As used herein, the term “non-isomorphic comonomers” means comonomers that disrupt a crystalline structure, typically because the comonomer size and shape does not allow the comonomer to fit into the crystalline structure of the other comonomers.
It is obvious, of course, that a particular comonomer may be isomorphic in
Dunbar Richard A.
Martin Donald H.
Williams, Jr. L. Peter
Edwards N
Howrey Simon Arnold & White , LLP
Solutia Inc.
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