Stock material or miscellaneous articles – Pile or nap type surface or component – Composition of pile or adhesive
Reexamination Certificate
1997-09-12
2004-04-06
Juska, Cheryl A. (Department: 1771)
Stock material or miscellaneous articles
Pile or nap type surface or component
Composition of pile or adhesive
C428S369000, C428S364000
Reexamination Certificate
active
06716511
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to propylene polymer fibers and yarns, articles of manufacture comprising the same, and manufacture thereof.
BACKGROUND OF THE INVENTION
Polypropylene fibers and yarns are well-known and are widely used in textile and other applications owing to a desirable combination of features. These include low cost, ease of processing, strength, chemical inertness and hydrophobicity. Examples of textile applications for the fibers and yarns include backing fabrics and pile or face yarns for carpets; upholstery fabrics; geotextile fabrics; wallcover fabrics; automotive fabrics, such as carpets, trunk liners and kick panels; diaper cover stock; and apparel fabrics.
There is, and has long been, a need for improved polypropylene fibers and yarns for use in applications in which the fibers, yarns or textile products containing them are subjected to bending, creasing, wrinkling, compression and the like. Examples include apparel fabrics, fiberfill, carpets, upholstery fabrics and automotive fabrics. Poor resilience of fibers and yarns used in such applications can result in limited recovery from forces to which fibers and yarns are subjected in use and, in turn, poor aesthetics and wear. These may limit or even preclude utility for certain end uses.
A practical example of the impact of resilience on utility of fibers and yarns for a given purpose is provided by experience in the United States carpet industry. Deficient resilience of carpet face yarn leads to poor thickness retention and recovery of pile height after application of compressive forces, such as those resulting from foot traffic and placement of furniture. Other things being equal, carpet with less resilient face yarn will take on a matted and clumped appearance, show wear and need to be replaced more rapidly and to a greater extent than that tufted with more resilient yarns. Similarly, depressions caused by placement of furniture or other objects will recover more slowly, if at all, in carpets with face yarn of low resilience.
These problems have long been recognized and many attempts at solving them have been advanced over the years. Modified polymer compositions and crystallinities have been proposed by polymer producers. Enhanced fiber spinning processes and yarn treatments have been explored by yarn manufacturers. Carpet manufacturers have developed modified carpet constructions. Despite these efforts and advances resulting from some of them, the long felt need for polypropylene fibers and yarns of improved resilience continues. Indeed, despite a combination of cost, colorfastness, stain resistance, mold and mildew resistance and ease of cleaning that is superior to other carpet face yarns, commercial success of polypropylene yarns in the carpet industry has been elusive. The yarns account for only about 25% of overall carpet face yarn usage and considerably less in residential carpets.
In greater detail, carpet sales in the United States in 1992 were about 1.25 billion square yards according to the Carpet & Rug Institute. Of that total, about 65% was so-called residential carpet, e.g., for housing. The balance was so-called commercial carpet, e.g., for office buildings, schools, stores and airports. Major face yarn types currently used for both types of carpet are nylon yarns, normally composed of polyepsilon-caprolactam or polyhexamethylene adipamide, also known as nylon 6 and 66, respectively; polyester yarns, normally composed of polyethylene terephthalate; and polypropylene yarns, typically composed of crystalline homopolymer polypropylene. In 1993, according to
Carpet
&
Rug Industry Review
, October, 1993, total United States carpet face yarn sales were about 2.9 billion pounds, with nylon yarns accounting for about 65%, polypropylene yarns accounting for about 25%, and polyester yarns accounting for about nine %. Wool, cotton and other yarns accounted for less than one %.
Nylon yarns are and have been the dominant synthetic face yarns for both residential and commercial carpets. However, polypropylene yarns' usage in commercial carpets has increased from essentially nothing in the late 1970's to about 40% as of 1992. This growth can be attributed to a combination of factors. One is the superior performance characteristics noted above. In addition, polypropylene yarns typically are less costly than nylon yarns, not only in cost per unit weight of yarn, but even more so in cost per unit area of coverage, because, for a given yarn type, polypropylene yarns have lower density than nylon yarns. The volume of a given weight of polypropylene yarn exceeds that of the same weight of nylon yarn; accordingly, polypropylene yarns provide greater coverage per unit weight and, in turn, per unit cost. Also contributing to the growth in acceptance of polypropylene yarns are various yarn configurations and features of carpet construction developed over the years that compensate to some extent for the yarns' lower resilience.
In the area of carpet manufacture, elements of construction that compensate somewhat for poor resilience include so-called loop pile constructions, low pile heights and high tuft densities. In loop pile constructions, face yarn tufts that form the carpet's pile surface are left uncut, such that the tufts are disposed in loops on the pile surface. Other things being equal, looped tufts have greater resistance to compression and better recovery than cut pile tufts. Low pile height limits the effect of compressive forces, in any event, by providing shorter tufts to compress. High tuft density, that is, many tufts per unit area of pile surface, makes for close spacing of tufts to one another such that the tufts and their fibers provide support to neighboring tufts and fibers to thereby resist and recover from compression.
In terms of yarn configuration, twisted yarns normally are more resilient than untwisted yarns, with tighter twist and greater twist retention providing greater resilience, other things being equal. Levinstein,
The Complete Carpet Manual
, 1992, pp. 44-45. It is also known that twist retention can be improved by subjecting yarns to bulking treatments, such as texturizing with fluid jets or crimping, before or after twisting. Those treatments are normally conducted primarily to impart bulkiness and texture to yarns by creating whirls, loops, entanglements, waviness, kinks and crimp in their filaments. Through such interaction of the textured filaments, twist retention in twisted yarns, as well as resilience of even untwisted yarns, are typically improved. Heatsetting often is employed to set, or lock in, twist and bulk. As an example of these types of yarn configurations, U.S. Pat. No. 4,290,378 (1981) of Monsanto discloses “bulky, loopy, heatset, tangled, twisted singles yarn” which may be composed of polyamides (nylons), polyolefins, polyesters and polyacrylonitriles. The yarns are said to have exceptional column strength, resistance to bending and untwisting and to be useful in cut and loop pile carpets. So-called blended yarns, made up of filaments of greater and lesser resilience, e.g., nylon and polypropylene, also have been proposed for the purpose of obtaining yarns with greater resilience than that of yarns composed entirely of the less resilient filaments, as noted in U.S. Pat. No. 3,295,308 (1967) of Eastman Kodak. Yarns composed of so-called bicomponent fibers, such as sheath-core fibers having a core of nylon surrounded by a sheath of polypropylene, also have been proposed as a means to combine the resilience of nylon with the superior properties of polypropylene in other respects.
As a result of some of these yarn configurations and carpet constructions, together with polypropylene yarns' price and performance advantages, polypropylene yarns have gained in acceptance as face yarn for commercial carpets. Of course these techniques do not improve resilience of polypropylene fibers per se, nor do they significantly close the gap between nylon and polypropylene in terms of fiber resilience or pile height recovery of t
Bersted Bruce Howard
Norris, Jr. Richard Tutt
Slutsker Leonid
Stokes Ty Jackson
BP Corporation North America Inc.
Hensley Stephen L.
Juska Cheryl A.
LandOfFree
Propylene polymer fibers and yarns does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Propylene polymer fibers and yarns, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Propylene polymer fibers and yarns will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3205423