Carpet yarn desensitized to variable ambient environmental conditions and methods and systems of making the same

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

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

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

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.

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.

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.

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

Reference will hereinafter be made to the accompanying drawings wherein like reference numerals throughout the various FIGURES denote like structural elements, and wherein:

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.

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

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

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.

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.

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.

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.

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.

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 & Co. KG.

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.

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 & 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-H₂O 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.

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.

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 48-2a surrounded by a pair of lateral guide arms 48-2a (only one of such arms 48-2a being depicted in the cross-sectional view of FIG. 2). A supply channel 48-2c fluid-connects a supply inlet port 48-2d to the surface 48-2a. The supply inlet port 48-2d 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 48-2d and is discharged onto the surface 48-2a 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 48-2a 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.

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.

The present invention will be further understood by reference to the following non-limiting Example.

EXAMPLE 1

Comparative

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).

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.

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

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).

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.

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

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.

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.

Claims

1. A method of making environmentally desensitized polymeric yarn comprising the sequential steps of:

(i) melt-spinning a polymer to form a multi-filament yarn;

(ii) drawing and texturizing the melt-spun yarn;

(iii) applying an environmentally desensitizing sufficient amount of water to the drawn and textured yarn by bringing the yarn into contact with a substantially constant flow of water supplied to the yarn by a non-peristaltic pump; and thereafter

(iv) collecting the drawn and texturized yarn.

2. The method of claim 1, wherein step (iii) is practiced so as to apply greater than about 3.5 wt. % water add-on to the yarn, based on total yarn weight.

3. The method of claim 2, wherein the water add-on is between about 4 to about 10 wt. %.

4. The method of claim 2, wherein the water add-on is between about 5.0 to about 8.0 wt. %.

5. The method of claim 2, wherein the step (i) comprises melt-spinning a nylon-6 or nylon 6,6 polymer, and wherein the water add-on according to step (iii) is between about 6.0 to about 7.0 wt. %.

6. The method of claim 1, wherein step (ii) is practiced by drawing the yarn between first and second heated rolls to achieve a draw ratio of between about 1.4 to about 3.6.

7. The method of claim 6, comprising heating the first and second rolls so that the second roll is between about 70° C. to about 190° C. greater than the first roll.

8. The method of claim 7, wherein the multifilament yarn is nylon-6 and wherein the first roll is heated to a temperature of between about 50 to about 70° C., and wherein the second roll is heated to a temperature between about 170 to about 200° C.

9. The method of claim 7, wherein the multifilament yarn is nylon 6,6 and wherein the first roll is heated to a temperature of between about 50 to about 100° C., and wherein the second roll is heated to a temperature between about 170 to about 240° C.

10. The method of claim 1, wherein step (iv) comprising winding the yarn onto a spool.

11. The method of claim 10, further comprising the step of (v) placing the yarn spool in a moisture controlled environment.

12. The method of claim 11, wherein said step (v) comprises wrapping the yarn spool in a moisture-proof plastics film.

13. A system for making environmentally desensitized polymeric yarn comprising:

a melt-spinning unit to form a melt-spinnable polymer into multi-filament yarn;

a draw texturing unit for drawing and texturizing the melt-spun yarn;

a water applicator unit for applying an environmentally desensitizing sufficient amount of water to the drawn and textured yarn, said water applicator unit comprising a yarn guide having a surface against which the yarn is adapted to contact, an aperture having an opening onto the yarn guide surface to allow water to contact the yarn, and a non-peristaltic pump for supplying a substantially constant flow of water to the aperture in the yarn guide; and

(iv) a winder for collecting the drawn and texturized yarn.

14. The system of claim 13, wherein said draw texturing unit comprises first and second heated rolls operable to achieve a draw ratio of between about 1.4 to about 3.6.

15. The system of claim 13, wherein the water applicator unit comprises a stationary applicator guide having a convex guide surface for guiding the drawn and textured yarn, an inlet port for receiving the constant uninterrupted stream of water from the non-peristaltic pump, and a supply channel fluid-connecting the inlet port to the guide surface wherein water is supplied to the drawn and textured yarn being guided thereby.

16. The system of claim 15, further comprising a head tank for providing an available supply of water to the nonperistaltic pump at substantially a constant pressure.

17. The system of claim 16, wherein the head tank maintains the supply of water at a relatively low pressure of less than about 10 inches-H2O.

18. A drawn and textured yarn exhibiting less environmental sensitivity which is made by the method of any one of claims 1-9.

19. A yarn spool made by the method of any one of claims 10-13.