Textiles: manufacturing – Thread finishing – Fabrication-defabrication
Reexamination Certificate
1999-09-09
2001-11-27
Vanatta, Amy B. (Department: 3765)
Textiles: manufacturing
Thread finishing
Fabrication-defabrication
C028S220000, C028S247000
Reexamination Certificate
active
06321427
ABSTRACT:
BACKGROUND
Knit-deknit yarns have been used as carpet face yarns to provide body and texture in carpet products produced therefrom.
Conventional methods for making such yarn involve knitting an extruded, fibrillated polyolefin tape yarn into a sock on a circular knitting machine. The sock is then heat treated to heat set kinks in the yarn of the knitted sock. The yarn is then deknit and wound for shipment. In use, the yarn may be formed into carpet, for example, by conventional tufting techniques and heat treated to cure the backing.
Conventionally, knit-deknit carpet yarns are of 5000 Denier (“D”) or less. A typical product is 2200 D yarn knitted with 18 needles on a 90 slot, 6.25″ diameter knitting machine such as an UNRAV CY-600, or an L-R Machine Model 6-CK circular knitting machine from Larry Rankin Machinery Co. On occasion, heavier product has been known in the prior art, i.e. a 5700 D product knitted with 30 needles, a 5000 D product knitted with 45 needles a 7,600 high density polyethylene yarn knitted with 22 needles and a 10,000 yarn knitted with 15 needles.
While these prior art yarns were acceptable for use in carpets, a need exists for yarns which would provide improved face yarns, particularly in high-end carpet products such as artificial turf sports surfaces.
OBJECTS AND SUMMARY OF THE INVENTION
It is an object of the present invention to provide a heavier grade of polymer carpet yarn having a heat set topology suitable for carpet products.
It is another object of the present invention to provide a yarn for carpet product having a dense, attractive yarn pile surface.
It is another object of the present invention to provide a carpet yarn having a non-directional, highly resilient pile.
It is another object of the present invention to provide methods and apparatus for making such yarns.
Applicants' initially believed that yarn of Denier greater than about 5700 (particularly relatively stiff polypropylene yarn) could not be densely knit and commercially produced on conventional knitting machines, at a needle count of greater than 22 on a 6.25 inch diameter circular knitting machine. However, applicants demonstrated that a fibrillated polymer yarn of, for example, 7600 D could be knitted into a sock at a needle count of 30. A conventional yarn lubrication applicator and conventional sock take-up machinery was provided with variable speed and tensioning to inhibit needle breakage in the knitting machine.
The resulting sock is densely knitted. The sock is heat treated to produce a heavy denier product with a high number of kinks per inch. The yarn is wound during which a twist may be imparted and the kinks straightened. When formed into carpet and heat-treated, the yarn blooms and produces a cut pile with a novel upper surface characterized by a dense array of yarn fibril ends having essentially random orientation. The carpet product also exhibits high resilience.
Preferred embodiments of the present invention include a process for making a carpet yarn. A fibrillated polyolefin yarn greater than 7000 in Denier; and preferably 7600 D to 8000 D is used. For example, the yarn may be 8000 D extruded polypropylene tape, 700 mils wide and 2.1 mils thick, slit to produce a fibrillated yarn. However, deniers of above 10,000, for example 11,000 D or 12,000 D may be used.
The yarn is knitted into a fabric or sock using a needle spacing less than one inch, preferably less than ⅔ of an inch. The sock is heat treated following which the sock is de-knitted.
Advantageously the process is performed using a 90 needle slot, circular knitting machine set up with 30 needles. Typically, such a circular knitting machine is a 6.25 inch diameter machine with a circumferential needle spacing of about 0.65″ or less.
The knitting may result in a knitted sock with a loop width of about 0.25 inches. Advantageously, the yarn is heat set in sock form, deknitted, wound, transported to the carpet manufacturing line, unwound and tufted as face yarn in a pile carpet. The carpet is further heat treated which restores the general kinked form of the yarn.
The present invention is also a carpet yarn of at least 7000 D extruded, fibrillated polyolefin tape having at least two kinks per inch of yarn in the finished carpet.
A further aspect of the invention is an apparatus for making the novel yarns disclosed herein. A preferred embodiment of the apparatus includes a supply of polymer yarn of at least 7000 D. The yarn is lubricated in a conventional fashion and fed to a multi-needle circular knitting machine where it is knitted into a sock preferably having a stitch length less than about one inch. A variable drive pull roller of a type known in the art is employed to pull the sock from the knitting machine at a selectable speed and tension to inhibit breakage of the knitting machine needles. An autoclave is used to heat treat the sock at for example 230° F. The yarn sock is deknitted after heat treatment and wound. After tufting, the yarn is further heat treated causing it to take on a repeating curvilinear form, especially a generally sinusoidal form. In preferred embodiments, the yarn in the finished carpet product has a repeat length or wavelength &lgr;, approximately equal to or less than the pile height of the carpet.
The foregoing is intended as a convenient summary of subject areas described in this patent specification. However, the invention to be protected is defined by the claims herein.
REFERENCES:
patent: 2857651 (1958-10-01), Keen
patent: 3496259 (1970-02-01), Guenther
patent: 3496260 (1970-02-01), Guenther et al.
patent: 3579764 (1971-05-01), Kieffer
patent: 3720984 (1973-03-01), Roberson, Jr.
patent: 3997950 (1976-12-01), Gibson
patent: 4005569 (1977-02-01), Corbiere
patent: 4137615 (1979-02-01), Webster
patent: 4181762 (1980-01-01), Benedyk
patent: 4870839 (1989-10-01), Odham
patent: 5160347 (1992-11-01), Kay et al.
patent: 23290 (1988-05-01), None
Manual: Model 6-CK Circular Knitting Machine, L-R Machine Sales, Inc., Chickamauga, Georgia 30707.
Manual: Model CY-600 Lab-Knit, Speizman Industries, Inc., Charlotte, North Carolina 28201.
Auguste Jean-Claude
Chiles Fred
Fink Wilbert E.
Burns Doane Swecker & Mathis L.L.P.
Polyloom Corporation of America
Vanatta Amy B.
LandOfFree
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