Abstract:
Carpet yarn is provided which is significantly less sensitive to changing ambient environmental conditions. As such, the carpet yarns exhibit substantially uniform wet bulk properties across a wide range of ambient temperature and/or atmospheric moisture conditions so as to reduce significantly (if not eliminate entirely) visible streaks in carpets formed of such yarns. In especially preferred embodiments, the carpet yarns when made are subjected to a substantially higher draw ratio and a substantially higher precrimp temperature prior to being brought into contact with water supplied by means of a non-peristaltic, continuous pressure, steady stream pump. The resulting yarn moisture content is increased to a greater level as compared to conventional carpet yarns not possessing the environmental desensitivity exhibited by the yarns of the present invention.

Description:
DOMESTIC PRIORITY CLAIM  
       [0001]     The present application is based on, and claims domestic priority benefits under 35 USC §119(e) from, U.S. Provisional Application Ser. No. 60/566,924 filed on May 3, 2004 (the entire content of which is expressly incorporated hereinto by reference). 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention carpet yarns and methods and systems to make the same. More particularly, the present invention relates to carpet yarn which exhibits less sensitivity to changing ambient environmental conditions.  
       BACKGROUND AND SUMMARY OF THE INVENTION  
       [0003]     The production of textured carpet yarn is well known, for example, from U.S. Pat. No. 4,522,774 to Donnelly et al (the entire content of which is expressly incorporated hereinto by reference). However, carpet yarn, especially yarn employed for automotive carpets, is extremely sensitive to changes in ambient environmental conditions during processing, such temperature and atmospheric moisture conditions that accompany seasonal changes. In this regard, the temperature and/or moisture conditions within processing plants may vary greatly which can in turn greatly affect the appearance of the resulting carpet. Thus, for example, when carpet yarn which has aged (i.e., has been exposed to the ambient plant environmental conditions) is mixed with relatively freshly made carpet yarn, the resulting carpet can have visible streaks attributable to uneven and/or inconsistent yarn bulk between the two types of yarns.  
         [0004]     It would therefore be highly desirable if carpet yarn could be produced which is considerably less sensitive to changing ambient environmental conditions so that visible streaks and like imperfections could be significantly reduced if not eliminated entirely. It is toward providing such carpet yarn that the present invention is directed.  
         [0005]     Broadly, according to the present invention, carpet yarn is provided which is significantly less sensitive to changing ambient environmental conditions. As such, the carpet yarns of this invention exhibit substantially uniform wet bulk properties across a wide range of ambient temperature and/or atmospheric moisture conditions so as to reduce significantly (if not eliminate entirely) visible streaks in carpets formed of such yarns. In especially preferred embodiments, the carpet yarns of the present invention when made are subjected to a substantially higher draw ratio and a substantially higher precrimp temperature prior to being brought into contact with water supplied by means of a non-peristaltic, continuous pressure, steady stream pump. As such, the yarn moisture content is increased to a greater level as compared to conventional carpet yarns not possessing the environmental desensitivity exhibited by the yarns of the present invention.  
         [0006]     These and other aspects and advantages will become more apparent after careful consideration is given to the following detailed description of the preferred exemplary embodiments thereof.  
     
    
     BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS  
       [0007]     Reference will hereinafter be made to the accompanying drawings wherein like reference numerals throughout the various FIGURES denote like structural elements, and wherein:  
         [0008]      FIG. 1  is a schematic depiction of a presently preferred system which embodies an improved process for forming environmentally desensitized carpet yarns of the present invention.  
         [0009]      FIG. 2  is an enlarged cross-sectional schematic view of an applicator system that may be used in the system of the present invention; and  
         [0010]      FIG. 3  is a graph of percent moisture on yarn versus pump RPM comparing the moisture add-on performance of a non-peristaltic, continuous pressure, steady stream pump to a conventional peristaltic pump. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0011]     Accompanying  FIG. 1  depicts a system  10  which embodies an improved process for forming environmentally desensitized carpet yarns of the present invention. In this regard, a supply tank  12  containing a fiber-forming thermoplastic polymer in chip or flake form supplies a melt extruder  14  which forms a flowable melt of the thermoplastic polymer. Preferably, the thermoplastic polymer is a nylon, such as nylon 6, nylon 6,6 and the like. The melt flow of thermoplastic polymer is then directed to metering pumps  16  which deliver a metered flow of the thermoplastic polymer melt to the spinnerette  18 . As is well known, the melt flow of thermoplastic material is extruded through multiple orifices in the spinnerette  18  to form a corresponding plurality of filamentary polymeric strands  20 . Before entering the spinnerette orifices, the melt flow of polymer has been filtered, as is generally employed and well understood by those of skill in the art. The particular temperature for the polymer in the spinnerette  18  depends upon the type of polymer being spun as well as its molecular weight.  
         [0012]     Alternatively, the polymer may be made and spun in a one step process. That is, the polymer may be polymerized continuously from its constituent monomers and then fed as an already molten stream to the spinnerette. In such a case, of course, the melt extruder would not necessarily be employed.  
         [0013]     The molten filamentary polymeric strands  20  are quenched by means of a standard quench cabinet  22  which provides a flow of transversely moving cooling gas, especially air, as shown by the arrows. The thus solidified filamentary polymer strands are then configured into a close-packed, essentially monofilamentary layer so that a lubricating composition may be applied thereto by means of a finish applicator  24 . Virtually any conventional finish applicator  24  may be employed, such as those disclosed in U.S. Pat. No. 3,893,412 (the entire content of which is expressly incorporated hereinto by reference). Guides  26  are employed to direct the individual lubricated multifilamentary yarn around a standard, commercially available, unheated pre-tensioning godet and separator roll  28 .  
         [0014]     The pretensioned multifilamentary yarn is then supplied to a first set of heated duo rolls  30  and then to a second set of heated duo rolls  32  operating at yarn speeds at the duo rolls  32  of from about 2000 to about 4500 m/min, more preferably between about 2700 and about 3800 m/min. The yarn is thus drawn between the rolls  30  and  32  at a draw ratio of between about 1.4 (for high drawing speeds) to about 3.6 (for low drawing speeds), preferably between about 2.8 to about 3.6, and most preferably between about 3.0 to about 3.2. The temperature of the second set of duo rolls  32  is most preferably at least between about 70° C. to about 190° C. greater than the temperature of the first set of duo rolls  30 . Thus, for example, when processing nylon-6 yarns, a temperature of between about 50 to about 70° C. for the first set of duo rolls  30  is desirable, whereas a temperature of between about 170 to about 200° C. (advantageously about 190° C.) for the second set of duo rolls  32  is desirable. Where processing nylon 6,6 yarns, a temperature of between about 50 to about 100° C. for the first set of duo rolls  30  is desirable, whereas a temperature of between about 170 to about 240° C. for the second set of duo rolls  32  is desirable. This relatively high draw ratio achieved between the first set of duo rolls  30  and the second set of duo rolls  32  and the relatively high precrimp temperature achieved at the second set of duo rolls  32  is believed to decrease substantially the sensitivity of the resulting carpet yarn when the yarn also exhibits a relatively high moisture content.  
         [0015]     Although the duo roll  30  is depicted in  FIG. 1  as comprising a set of rolls, the process and systems in accordance with the present invention may be advantageously practiced with a single heated roll and an idler roll providing similar functions.  
         [0016]     The drawn and precrimped yarn is then directed to a conventional texturing unit  34  in order to produce a relatively bulky yarn which is discharged in crimped form onto a commercially available cooling drum  36 . Directing the threadline into the individual texturing unit  34  can be conveniently accomplished by means of the devices disclosed in U.S. Pat. No. 4,280,260 (the entire content of which is expressly incorporated hereinto by reference). The texturing unit  34  is preferably a fluid jet texturing unit well known to those of skill in the art and exemplified by U.S. Pat. No. 6,141,843, the entire content of each being expressly incorporated hereinto by reference. One particularly preferred texturizing unit is Model No. STM-25 commercially available from Barmag/Saurer GmbH &amp; Co. KG.  
         [0017]     The textured yarn is removed from the cooling drum  36  by means of guide roll  38  and takeaway godet  40 . The textured yarn is passed through a conventional fluid interlacer jet  42  to as to entangle the individual filaments in the yarn. The fluid interlacing jet may be, for example, those disclosed in U.S. Pat. Nos. 3,115,691 and 3,125,793, the entire content of each being expressly incorporated hereinto by reference. The interlaced yarn is then directed via rolls  44  to a compensator  46  which facilitates winding of the yarn onto a take-up spool at the winder  56 .  
         [0018]     Important to the present invention, however, is that prior to being wound onto the take-up winder  56 , the moisture content of the yarn is increased by bringing the yarn into contact with water applied via a water applicator assembly  48 . In this regard, deionized water at a substantially constant flow rate is supplied to the applicator assembly  48  by means of a non-peristaltic, continuous pressure, steady stream pump  50 . One particularly preferred pump  50  is Model SPX-12-0500S1 commercially available from Slack &amp; Parr Ltd. of Derby, England. The pump  50  supplies a constant uninterrupted stream of water at a relatively low pressure of less than about 10 inches-H 2 O which is maintained by head tank  52 . Make-up deionized water is supplied to the tank  52  via valve  54 . An increased moisture content is thereby imparted to the filaments in the textured yarn by virtue of the applicator assembly  48 .  
         [0019]     The yarn spool at the winder  56  is most preferably encased in a sealed moisture-proof plastic envelope (not shown) and allowed to age for a few days, e.g., for about 1 day up to about 14 days, and more preferably at least about 7 to about 10 days. Alternatively, the yarn spool may be placed in a rigid moisture-proof container so as to seal it against water evaporation and/or placed in a humidity controlled atmosphere (e.g., a room or enclosure having between about 80 to about 100% relative humidity atmosphere). When wrapped with a moisture-proof plastic envelope, it is presently preferred to use a film formed of a polyolefin (e.g., polypropylene) having a sufficient thickness and/or wrapped a sufficient number of time to achieve the moisture-proof envelope that is desired. Especially preferred films for such purpose include 0.8 mil thick polypropylene film which is wrapped around the package several turns (e.g., about three turns). Multiple yarn spools are most preferably wrapped by the film. In this manner, the yarn on the spool will be further exposed to its own high moisture content environment within the envelope thereby facilitating its take-up of moisture to achieve the desired high moisture content as noted above.  
         [0020]     An especially preferred water applicator assembly  48  is depicted in cross-sectional schematic fashion in accompanying  FIG. 2 . In this regard, the water applicator assembly includes a winged wheel  48 - 1  to direct the textured yarn to a stationary applicator guide  48 - 2 . The applicator guide  48 - 2  includes a smooth convex surface  48 - 2   a  surrounded by a pair of lateral guide arms  48 - 2   a  (only one of such arms  48 - 2   a  being depicted in the cross-sectional view of  FIG. 2 ). A supply channel  48 - 2   c  fluid-connects a supply inlet port  48 - 2   d  to the surface  48 - 2   a.  The supply inlet port  48 - 2   d  is in turn fluid-connected to the non-peristaltic pump  50 . Thus, a constant uninterrupted stream of water at a relatively low pressure is fed into the inlet port  48 - 2   d  and is discharged onto the surface  48 - 2   a  where it contacts the traveling textured yarn being guided therealong. The supply of water is thus picked up by the traveling textured yarn prior to proceeding to the winder  56 . Excess water which is discharged to the surface  48 - 2   a  but which is not picked up by the traveling textured yarn is captured within an anti-spray housing (not shown) surrounding the applicator assembly  48  and recycled for further use.  
         [0021]     It has been found according to the present invention that an increased moisture content of greater than about 3.5 wt. %, preferably between about 4 to about 10 wt. % (based on the total yarn weight), and more preferably between about 5.0 to about 8.0 wt. % yields carpet yarn which is dramatically less sensitive to ambient environmental conditions or temperature and/or atmospheric moisture (relative humidity). When the multifilamentary yarn is formed of nylon-6 filaments, it has been found that a moisture content of between about 6.0 to about 7.0 wt. % (+/−about 0.5 wt. %) is especially desirable.  
         [0022]     The present invention will be further understood by reference to the following non-limiting Example.  
       EXAMPLE 1  
     Comparative  
       [0023]     A 1400 d solution dyed nylon-6 automotive carpet yarn was made with 3% (Low) water addition using a peristaltic pump. The conditioned yarn was packaged in two stretch wrap units and aged in inventory for 10 days. After the initial 10 days, one of the stretch wrap units was opened and stored in a controlled environment of 85% relative humidity (Wet). The other stretch wrap unit of the Low water addition conditioned yarn remained sealed in the stretch wrap (Dry).  
         [0024]     After humid conditioning for 10 days, the Wet yarn samples were tufted into the same carpet with the Dry yarn samples. The Wet and Dry yarn samples were arranged in bands so that they could be compared side-by-side.  
         [0025]     The wet yarn in the carpet appeared visually darker due to crimp relaxation in the humid environment. Likewise the dry yarn in the carpet appeared lighter since it has not been exposed to environmental moisture.  
       EXAMPLE 2  
     Invention  
       [0026]     Example 1 was repeated using a 1400 d solution dyed automotive yarn was conditioned with 6% (High) water addition using a non-peristaltic, continuous pressure, steady stream pump. The conditioned High water addition yarn was packaged in two stretch wrap units and aged in inventory for 10 days. After the initial 10 days, one of the stretch wrap units was opened and stored in a controlled environment of 85% relative humidity (Wet). The other stretch wrap unit of High moisture addition yarn remained sealed in the stretch wrap (Dry).  
         [0027]     After humid conditioning for 10 days, the Wet yarn samples were tufted into the same carpet with the Dry yarn samples. The Wet and Dry yarn samples were arranged in bands so that they could be compared side-by-side.  
         [0028]     The yarn in the carpet with 6% (High) water add-on exhibited less contrast wet to dry (light to dark) as compared to the 3% (Low) water add-on yarn. The additional water content which was added to the yarn by means of the present invention thus desensitized the yarn from the environmental difference.  
       EXAMPLE 3  
     Invention  
       [0029]     The moisture add-on effects of peristaltic and non-peristaltic pumps were examined using 1400 d solution dyed nylon-6 automotive carpet yarn. The results graphically appear in  FIG. 3 . As shown, all other parameters being equal, a non-peristaltic pump achieves greater water add-on to the yarn as compared to a peristaltic pump at all pump RPM outputs. Furthermore, by using a non-peristaltic pump, a greater maximum water add-on as compared to conventional peristaltic pumps is possible.  
         [0030]     While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.