Yarn having variable shrinkage zones

Abstract

A multi-filament yarn including interlace nodes disposed along the length of the yarn. The yarn has variable retained heat shrinkage potential at segments along its length such that segments of said yarn containing the interlace nodes have a retained heat shinkage potential in excess of segments of said yarn between the interlace nodes. Upon application of uniform heat to the yarn, the segments containing the interlace nodes exhibit enhanced shrinkage and self texturing relative to the segments between the interlace nodes.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of prior copending U.S. application Ser. No. 10/613,240, filed Jul. 3, 2003 entitled Pile Fabric and Heat Modified Fiber and Related Manufacturing Process and a continuation-in-part of prior copending U.S. application Ser. No. 10/613,241 filed Jul. 3, 2003 entitled Method of Making Pile Fabric the contents of all of which are incorporated by reference herein in their entirety.

TECHNICAL FIELD

The present invention relates generally to fabric formation yarns and more particularly to multifilament yarns in which discrete segments along the length undergo enhanced selective shrinkage resulting in self texturing and reduced crystalline orientation relative to other portions of the same yarn. A method of imparting the variable performance characteristics to the yarns is also provided.

BACKGROUND OF THE INVENTION

In the past, partially oriented yarns (POY) of multi-filament construction have typically been drawn and heatset under tension so as to extend and orient the individual filaments. In such a process each of filaments in the yarn is subjected to a substantially uniform heating and extension treatment such that the yarn will thereafter act in a uniform manner upon post fabric formation treatments such as heat setting, dyeing and the like. That is, since the yarn has been uniformly treated it does not exhibit variable response characteristics in a fabric when subjected to heating or other treatment conditions.

It is also known to under draw yarns under uniform heat treatment to less than full orientation for subsequent formation into a fabric. Such a process is illustrated and described in U.S. Pat. No. 5,983,470 to Goineau the contents of which are incorporated herein by reference in their entirety. The resultant fabric has a generally striated appearance upon dyeing.

SUMMARY OF THE INVENTION

According to one aspect, the present invention provides advantages and alternatives over the known art by providing a fabric formation yarn having variable shrink characteristics at different segments (also referred to as zones) along its length such that when such yarn is subsequently subjected to heat such as in fabric finishing treatments, discrete portions of the yarn undergo selective shrinkage and self texturing. The shrinking of segments along the yarn yields unshrunken yarn segments of substantially parallel, oriented fibers in combination with shrunken yarn segments of self textured filaments with reduced crystalline orientation in the same yarn.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described by way of example only, with reference to the accompanying drawings which constitute a portion of the specification herein and wherein:

FIG. 1 illustrates schematically a practice for hot drawing a multi-filament yarn to impart variable shrink characteristics at zones along the length of such yarn;

FIG. 2 is a block diagram setting forth steps for forming a variable surface texture fabric;

FIG. 3 illustrates a partially oriented non-textured multi-filament yarn prior to hot drawing;

FIG. 4 is a graphical representation illustrating the cross-sectional profile of yarn filaments at different zones along the length of the yarn of FIG. 3 during hot drawing;

FIG. 5 is a photomicrograph of a circular knit sock illustrating variable shrinkage segments of a fabric formation yarn;

FIGS. 6A and 6B are x-ray diffraction patterns for high shrink and low shrink portions of a formation yarn respectively;

FIGS. 7A and 7B are angular distribution plots of select diffraction peaks for high shrink and low shrink portions of a formation yarn respectively;

FIG. 8 illustrates a tricot knit fabric incorporating a fabric formation yarn with variable shrinkage segments following hot drawing and post formation heat treatment wherein zones of the fabric formation yarn have undergone selective shrinkage and self texturing;

FIG. 9 is a photomicrograph of fiber cross-sections in low shrink portions of a formation yarn according to the present invention; and

FIG. 9A is a photomicrograph of fiber cross-sections in high shrink portions of a formation yarn according to the present invention at the same magnification as FIG. 9.

While the present invention has been generally described above and will hereinafter be described in greater detail in relation to certain illustrated and potentially preferred embodiments, procedures and practices it is to be understood that in no event is the invention to be limited to such illustrated and described embodiments, procedures and practices. Rather, it is intended that the invention shall extend to all embodiments, practices and procedures as may be embodied within the broad principles of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, according to a potentially preferred practice of the present invention a yarn sheet 130 formed from a plurality of yarns 122 is passed from a creel 131 through a drawing apparatus 132 to a take-up 133. The yarns 122 are so called “partially oriented yarns” of multi-filament construction wherein the filaments 126 (FIG. 3) have been interlaced at discrete zones along the length of the yarn. In practice it is contemplated that the yarns are formed from a heat shrinkable material, such as a thermoplastic. By way of example only and not limitation, exemplary fiber materials may include polyester, polypropylene, nylon and combinations thereof. As will be appreciated, when such materials are extruded from a melt solution into drawn filaments, those filaments have an intrinsic finite shinkage potential which is activated upon subsequent heat exposure. During heat exposure shinkage will proceed until the shinkage potential is exhausted or the heating is terminated.

As shown, the drawing apparatus 132 has a first draw zone 136 located between tensioning rolls 138, 140 and a second draw zone 142 located between tensioning rolls 140 and 146. A contact heating plate 150 as will be well known to those of skill in the art engages the yarns 122 within the second draw zone 142. According to the potentially preferred practice, the partially oriented yarns 122 are passed through the first draw zone 136 with substantially no heating or drawing treatment. Thus, the yarns 122 are substantially unaltered upon entering the second draw zone 142. At the second draw zone the yarns 122 preferably undergo a relatively slight drawing elongation while simultaneously being subjected to a relatively low temperature heating procedure from the contact heater 150. Since the resultant yarn 122′ is not drawn to a condition of full orientation it is referred to as “underdrawn” yarn.

According to the potentially preferred practice the yarn is conveyed across the contact heater 150 at a high rate of speed such that the yarn does not reach a state of temperature equilibrium within the cross-section of the yarn at all segments along its length. By way of example only, and not limitation, for a 115 denier polyester yarn it has been found that subjecting such yarn to a draw ratio of about 1.15 (i.e. 15% elongation) with a contact heater temperature of about 170 C. to about 200 C. with a take up speed of about 500-600 yards per minute provides the desired non-uniform cross-sectional heat treatment at some segments of the yarn while yielding a uniform cross-sectional heat treatment at other segments. Of course, the level of drawing, temperature and speed may be adjusted for different yarns.

The resultant yarn 122′ may then be formed into a fabric and heat treated to provide desired surface characteristics in the manner as will be described further hereinafter. Of course, it is also contemplated that the yarn 122′ may be subjected to heat treatment prior to introduction into a fabric if desired. In either case, discrete segments of the yarn 122′ undergo shrinkage and self-texturing while other segments along the same yarn experience little if any change.

The mechanism believed to be responsible for the non-uniform character of the yarns is believed to relate to the nature of the partially oriented yarn 122 being processed as well as the process conditions. Referring to FIG. 3, a representative illustration is provided of a partially oriented yarn (POY) 122 such as may be treated according to the practice described above. As illustrated, the yarn 122 of partially oriented construction is characterized by loose segments 151 in which the individual filaments 126 are disposed in generally parallel aligned loose orientation relative to one another. These loose segments 151 are interspersed by discrete interlace nodes 152 in which the filaments are interlaced in a more compacted relation so as to hold the overall yarn 122 together. The cross-sectional heat transfer characteristics of the loose segments 151 are believed to be substantially different from that of the interlace nodes 152 and the yarn portions immediately adjacent such nodes.

In FIG. 4 a graphical illustration of the fiber cross-section is provided showing the relative response of the filaments 126 in the loose segments 151 and interlace nodes 152 of the yarn during heating under slight draw conditions as described above. In particular, what is seen is that the filaments within the loose segments 151 are pulled towards the heater by a combination of tensioning and heat shrinkage so as to assume a relatively low cross-sectional profile orientation across the contact heater 150. This low cross-sectional profile allows those zones to receive a substantially uniform and complete heat treatment despite the high speed of travel across the heater. Conversely, the relatively slight degree of draw applied is inadequate to pull out the interlace nodes 152. Thus, flattening and spreading of the filaments at the interlace nodes is avoided. Thus, upon high speed underdrawing conditions the yarn portions around the interlace nodes 152 retain a higher more concentrated profile across the heater 150 rather than flattening out like the loose segments 151.

It is surmised that due to the lack of flattening and the high rate of travel across the heater, heat treatment is not uniform within the interlace nodes and adjacent portions. Thus, a significant number of the filaments at those areas retain a relatively high level of shrinkage potential since a steady state temperature is not reached. The retention of such shinkage potential leaves such segments susceptible to subsequent enhanced heat shrinkage relative to the remaining portions of the yarn (which have been subjected to uniform temperature treatment) upon subsequent heat application.

Variable Shrinkage and Bulking Evaluation

The enhanced retained shrinkage potential of the yarn at the interlace nodes relative to the intermediate loose zones following the treatment process as outlined above has been confirmed by cutting out segments of an exemplary 260 denier polyester yarn treated according to the procedure outlined above and thereafter subjecting those cut out segments to a uniform heat treatment and then measuring the level of shrinkage caused by the heat treatment. In particular, a first group of two yarn segments was cut out from sections between interlace nodes such that each of the two cut out yarn segments in this first group was substantially devoid of any interlace node. A second group of three yarn segments was cut out from the yarn such that each of the three cut out yarn segments in this second group was formed substantially of a single interlace node. Both the first group and the second group of yarn segments were then subjected to a high temperature superheated steam treatment to observe shrinkage. The results are set forth in Table I below showing that the second group of yarn segments formed from the interlace nodes exhibited substantially increased shrinkage on a percentage basis relative to the yarn segments in the first group devoid of interlace nodes.

TABLE I
                                 Percent Shrinkage
Sample Segment                   After Heat Treating
Sample 1 - Interlace Node Segment 43%
Sample 2 - Interlace Node Segment 40%
Sample 3 - Interlace Node Segment 33%
Sample 4 - No Interlace Nodes    10%
Sample 5 - No Interlace Nodes    0%

In addition to shrinkage, it was also observed that the yarn segments formed from the interlace nodes underwent an enhanced degree of bulking and self texturing resulting in substantial filament thickening in a significant portion of the filaments.

Crystalline Orientation Evaluation:

It has also been found that after heat treatment (such as occurs in fabric finishing) segments of the same yarn treated according to the procedures as previously described are characterized by substantially different levels of crystalline orientation as measured by wide angle x-ray diffraction. In order to characterize the molecular structure of the two different types of domains in a finished construction, a polyester yarn treated according to the process as illustrated and described in relation to FIG. 1 was circularly knitted into a sock (i.e. a tube), dyed, and finished. The finished sock exhibited two distinct types of courses: open courses consisting of yarn that had low shrinkage during finishing, and tight courses consisting of yarn that had high shrinkage during finishing. FIG. 5 illustrates a zone in the sock containing these two regions. Importantly, it is to be understood that the same yarn is used throughout the sock and that the different zones emerged only after subsequent heat treatment.

To understand the differences in the zones of the sock individual courses of each type of region were removed from the construction for x-ray measurement. Courses were ‘double-folded’ to form a 4-ply yarn so as to increase the scattering signal rate and reduce the necessary exposure time. Samples were mounted onto standard x-ray sample mounts.

Wide-angle diffraction patterns were generated via exposure to x-rays generated with a rotating copper anode source having a primary wavelength of 1.5418 Å. Patterns were recorded using a general area detector system offset to an angle of 2θ=16.5° and set 15 cm from the sample position. Samples were oriented in the beam such that the fiber axis was vertical. Exposures of 15 minutes were used to generate patterns, and a background pattern acquired over an empty position on the sample holder was subtracted from the resulting data.

The diffraction pattern for the high-shrink yarn sample is shown in FIG. 6A and that for the low-shrink yarn is shown in FIG. 6B wherein the lighter zones identify higher reflection intensity levels. Qualitatively, it was observed that in the two patterns the crystal plane reflections (the broad intensity peaks) in the high-shrink sample have a greater azimuthal spread than those in the low-shrink sample. It is known that the two primary causes of azimuthal spreading in multifilament fiber samples are misalignment of individual filaments and differences in the angular distribution of crystallites between the samples. Great care was taken during sample preparation to properly parallelize the filaments, and a slight tension was applied to maintain good orientation during handling and measurement. Thus, it is very unlikely that filament disorientation alone can account for the differences in angular peak distribution observed in the patterns. Therefore, it was determined that the azimuthal spread reflects a real difference in the angular distribution of crystallites between the two samples.

It is known that the difference in the angular distribution of crystallites between the two samples can be quantified in terms of the Herman orientation function: $f_c=\frac{3\langle {\cos }^2\sigma \rangle -1}{2}$
where σ is the relative angle of the PET chain axis. As will be appreciated, the Herman orientation function is a measure of the orientation of PET chains within fiber crystallites with respect to the fiber axis direction. It assumes values ranging from +1 (perfectly oriented parallel to the axis) to 0 (perfectly random) to −½ (perfectly oriented perpendicularly). For cylindrically symmetric (on average) fibers, the distributional average of the square cosine term is given by: $\langle {\cos }^2\chi \rangle =\frac{{\int }_0^{\pi }{\cos }^2\chi I_P\left(\chi \right){\sin }_{\chi }d\chi }{{\int }_0^{\pi }{I}_P\left(\chi \right){\sin }_{\chi }d\chi }.$
Where I_P(χ) is the angular distribution of a directional vector P (in this case, the PET chain direction) as measured with respect to a reference direction, in this case the fiber axis.

In PET there does not exist a crystalline reflection in the direction of the PET chains. Thus, to determine the Herman orientation function for PET chains a well recognized geometric relationship is utilized to develop the square cosine term.
(cos² σ)=1−0.8786(cos² χ₍₀₁₀₎)−0.7733(cos² χ₍₁₁₀₎)−0.3481(cos² χ₍₁₀₀₎),
where σ is the relative angle of the PET chain axis, and χ_(hk0) are the relatives angles of the (hk0) crystalline reflections. This relationship was described by Z. Wilchinsky in Journal of Applied Physics 30, 792 (1959) the contents of which are incorporated herein by reference.

The <cos² χ_(hk0)> terms can be numerically computed by extracting the I_(hk0)(χ) distributions from the measured diffraction patterns. Angular distributions were computed by integrating the pattern signals over a 0.7° range of 2θ values centered on the following positions: 17.65° for the (010) reflection, 22.75° for the (110) reflection, and 25.35° for the (100) reflection. Distributions of x-ray peaks for the high shrink and low shrink yarn segments (used for purposes of integration) are shown in FIGS. 7A and 7B. Because of the limited detector area, distributions were extrapolated out to the full 180° range by assuming the signal at high angles was due solely to amorphous scattering. This amorphous baseline was subtracted from the distributions before numerical integration.

Results from the numerical determination of the Herman orientation function (ƒ_c) are shown in Table II below. As shown, the low-shrink yarn sample possessed a measurably higher level of orientation.

	TABLE II
		High Shrink	Low Shrink
	<cos{circumflex over ( )}2(θ100)>	0.060	0.038
	<cos{circumflex over ( )}2(θ110)>	0.087	0.062
	<cos{circumflex over ( )}2(θ010)>	0.108	0.083
	<cos{circumflex over ( )}2(σ)>	0.817	0.866
	Herman fc	0.725	0.799

In order to confirm the legitimacy of the crystalline orientation evaluations on the treated yarn of the present invention, a control analysis was conducted on a standard fully drawn 265 denier 36 filament partially oriented PET yarn that had been cold drawn with a 2.1 draw ratio and heat set at 220 C. Three samples were taken from segments 6 to 12 inches apart along the length of the yarn and x-ray patterns were generated using 45 minute exposures. An air scattering frame was also acquired and subtracted from the data before analysis. The same calculations were performed as described above. The Herman orientation function calculated based on the measurements of these samples ranged from 0.819 to 0.853 which is a difference of 0.034. This is less than half the difference of 0.074 measured for the high shrink and low shrink portions of the yarn. Thus, there exists a much greater variation in crystalline orientation between portions of the yarns of the present invention following heat treatment than in standard yarns.

Based on the evaluations carried out it may be seen that the interlaced nodes along the yarn give rise to the high shrink portions of the yarn. Moreover, upon application of heat treatment these high shrink portions shrink to a greater degree and have a lower level of crystalline orientation (as measured by the Herman Orientation Function) than the low shrink portions. Moreover, the degree of variation in crystalline orientation along the length of the yarns of the present invention is substantially greater than variations in standard yarns.

Fabric Formation:

As will be appreciated through reference to FIG. 2, subsequent to the introduction of variable heat treatment across portions of the yarn to introduce the above-described variable shrinkage characteristics, the yarn 122′ may thereafter be heat treated directly to release shrinkage potential or may be formed into a fabric for subsequent activation of heat. That is, the formation yarn 122′ may be formed into a greige fabric prior to activation of the self texturing and shrinkage characteristics. Activation may be effected by heat application such as during finishing and/or dying or any other suitable elevated temperature procedure. However, due to the variable heat treatment history at segments along the formation yarn 122′, when the formed greige fabric is heat set and/or dyed at prolonged elevated temperatures, segments of the fabric-forming yarn react in dramatically different fashions thereby imparting a variability to the finished fabric. In particular, portions of the yarns which made up the interlace nodes 152 and adjacent areas and which did not undergo a uniform heat treatment during drawing tend to undergo selective shrinkage and self texturing during the heat setting and/or dyeing operations. As explained above, this shrinkage occurs as a result of the fact that the shrinkage potential within these yarn segments has not been relieved previously. Conversely, the yarn portions which were in the loose portions of the yarn between the interlace nodes do not undergo substantial shrinking during the heat setting and dyeing operation since shrinkage potential has been relieved previously.

A resultant fabric structure following heat treatment and dyeing is illustrated in FIG. 8. As shown, although the same yarns 122′ are utilized throughout the face portion 116 of the fabric 110, discrete segments of those yarns have undergone shrinkage so as to form segments 160 of self textured entangled construction across the fabric. The segments of the yarns which have undergone uniform heat treatment during the initial drawing operation do not undergo such shrinkage and thus define arrangements of substantially unaltered surface loops 162 wherein the filaments remain substantially aligned with relatively low levels of crimping and entanglement.

As in the individual yarn samples evaluated, due to the shrinkage of the filaments at different yarn segments in the fabric, the filaments within the self textured segments 160 of the face are characterized by a substantially greater diameter than the filaments in the unaltered surface loops. By way of example only, for purposes of comparison photomicrographs are provided of filament cross sections in exemplary low shrink yarn portions (FIG. 9) as well as in self textured high shrink yarn segments (FIG. 9A).

It is contemplated that in order to realize the aesthetic and tactile benefits of the variable shrinkage zones in a formed fabric, the filaments making up the self-textured segments will preferably have an average diameter at least about 25 percent greater (more preferably at least about 50 percent greater) than the average diameter of the filaments forming the low shrink portions. For yarns formed from filaments with non-circular cross-sections the difference between the high shrink and low shrink portions may be measured in terms of cross-sectional area. For yarns formed from either circular or non-circular filaments, the high shrink segments will preferably have an average cross-sectional area at least about 1.56 times (more preferably at least about 2.25 times) the average area of the filaments forming the low shrink segments. In the illustrated exemplary constructions, a comparison of the filaments of FIGS. 9 and 9A shows that these levels are met and that some of the filaments in the self textured high shrink segments are at least twice the diameter of some of the filaments in the low shrink portions. Thus, for yarns formed from non-circular filaments it is contemplated that at least a portion of the filaments in the high shrink segments will have a cross-sectional area 4 times the area of some filaments forming the low shrink segments.

By way of example only, within a yarn 122′ according to the present invention it is contemplated that the number of interlace nodes will preferably be in the range of about 10 to 40 nodes per meter with each node taking up about 0.6 to about 1.3 cm. Thus, it is contemplated that zones of high retained shrinkage potential will preferably make up about 6% to about 52% percent of the total length of the yarn and will more preferably make up about 25% of the total length of the yarn.

A potential benefit of the present invention is that in a fabric the self-textured segments of heat shrunk yarn are arranged across the surface of the fabric in a substantially random arrangement. This imparts a substantially natural random look which may be desirable in many instances. Moreover, since the self-textured zones undergo heat shrinkage as a result of activating intrinsic heat shrink potential, such shrinkage occurs without embrittlement thereby enhancing a soft feel and avoiding filament breakage leading to undesirable shredding. In this regard it is to be understood that the terms “self texturing” or “self-crimping” refers to the characteristic that the filaments have a crimped construction after shinkage without the application of external crimping or texturizing procedures.

As previously indicated, after self-texturing takes place, the high shrink portions of the yarn have a lower level of crystalline orientation than the low shrink portions. In this regard it is contemplated that the level of crystalline orientation of the low shrink portions of the yarn as measured by the Herman Orientation Function will on average be at least 5% greater (and more preferably at least 10% greater) than the level of crystalline orientation of the high shrink portions.

The invention may be further understood through reference to the following non-limiting examples.

EXAMPLE I

A 115 denier 36 filament semi-dull round partially oriented polyester yarn was subjected to a 1.143 draw across a contact Dowtherm heater plate operated at a temperature of 200 C. The heater contact length was 17 inches and the yarn was taken up off of the heater at a rate of 600 yards per minute. The yarns were spaced at a density of approximately 17.4 yarns per inch across the heater. The warper tension was set at 25 to 30 grams. Overall draw ratio was 1.165. Measurements of the post drawn yarn indicated a linear density of 100.5 denier and a boiling water shrinkage of 14.7%. The drawn yarn was knitted into the face of a 2 bar Tricot knit fabric with the ground being formed of a 70 denier 36 filament semi-dull round fully warpdrawn polyester. The bar 1 (face yarn) runner length was 102 inches. The bar 2 (ground yarn) runner length was 46 inches. The knitting machine was fully threaded. The resultant fabric had 60 coarses per inch. The fabric was jet dyed according to a standard disperse dye cycle at 280° F., held for 20 minutes with a 2° F. per minute temperature ramp up. The fabric was wet pad tenter dried at a temperature of 300° F. passing through the tenter at 20 yards per minute. The exit width after drying was 59.5 inches. The resultant fabric had random high loops with relatively greater oriented crystalline regions than the low loops which were characterized by very low order orientation of the crystals as measured by wide angle X-ray scattering.

EXAMPLE 2

A 115 denier 36 filament semi-dull round partially oriented polyester yarn was subjected to a 1.143 draw across a contact Dowtherm heater plate operated at a temperature of 175 C. The heater contact length was 17 inches and the yarn was taken up off of the heater at a rate of 600 yards per minute. The yarns were spaced at a density of approximately 17.4 yarns per inch across the heater. The warper tension was set at 25 to 32 grams. Overall draw ratio was 1.165. Measurements of the post drawn yarn indicated a linear density of 100.0 denier and a boiling water shrinkage of 12.04%. The drawn yarn was knitted into the face of a 4 bar 56 gauge Raschel knit fabric. The bar 1 yarn (tie down stitch) bar 2 yarn (tie down stitch) and bar 4 (ground yarn) were all formed of 70 denier 36 filament semi-dull round fully warpdrawn polyester. The face yarn was threaded in Bar 3. The bar 1 runner length was 60 inches. The bar 2 runner length was 60 inches. The bar 3 (face yarn) runner length was 102 inches. The bar 4 runner length was 60 inches. The resultant fabric had 49.5 coarses per inch. The fabric was jet dyed at 280° F., held for 20 minutes with a 2° F. per minute temperature ramp up. The fabrics were wet pad tenter dried at a temperature of 300° F. passing through the tenter at 20 yards per minute. The exit width after drying was 53 inches. The resultant fabric had random high loops with relatively greater oriented crystalline regions than the low loops which were characterized by very low order orientation of the crystals as measured by wide angle X-ray scattering. The tiedown stitching pronounced the height of the higher loops.

Claims

1. A multi-filament yarn comprising a plurality of interlace nodes disposed along the length of said yarn, wherein said yarn is characterized by variable retained heat shrinkage potential at segments along its length such that segments of said yarn containing said interlace nodes have a retained heat shinkage potential in excess of segments of said yarn between said interlace nodes such that upon application of uniform heat to said yarn, the segments of said yarn containing said interlace nodes exhibit enhanced shrinkage and self texturing relative to the segments of said yarn between said interlace nodes such that following said application of uniform heat to said yarn, filaments within the segments of said yarn containing said interlace nodes are characterized by an average cross-sectional area at least 1.56 times the average cross-sectional area of yarn filaments in the segments of said yarn between said interlace nodes.

2. The invention as recited in claim 1, wherein said yarn is a multi-filament polyester yarn.

3. The invention as recited in claim 1, wherein said yarn is a multi-filament polypropylene yarn.

4. The invention as recited in claim 1, wherein said yarn is a multi-filament nylon yarn.

5. The invention as recited in claim 1, wherein said yarn comprises about 10 to 40 interlace nodes per meter along its length.

6. The invention as recited in claim 1, wherein the interlace nodes occupy about 6% to about 52% of the length along said yarn.

7. The invention as recited in claim 6, wherein the interlace nodes occupy about 25% of the length along said yarn.

8. A multi-filament yarn comprising a plurality of interlace nodes disposed along the length of said yarn, wherein said yarn is characterized by variable retained heat shrinkage potential at segments along its length such that segments of said yarn containing said interlace nodes have a retained heat shinkage potential in excess of segments of said yarn between said interlace nodes such that upon application of uniform heat to said yarn, the segments of said yarn containing said interlace nodes exhibit enhanced self texturing relative to the segments of said yarn between said interlace nodes and such that following said application of uniform heat to said yarn, the average level of crystalline orientation of filaments within the segments of said yarn between said interlace nodes as measured by the Herman Orientation Function is at least 5% greater than the average level of crystalline orientation of filaments within the segments containing said interlace nodes.

9. The invention as recited in claim 8, wherein the average level of crystalline orientation of filaments within the segments of said yarn between said interlace nodes as measured by the Herman Orientation Function is at least 6% greater than the average level of crystalline orientation of filaments within the segments containing said interlace nodes.

10. The invention as recited in claim 8, wherein the average level of crystalline orientation of filaments within the segments of said yarn between said interlace nodes as measured by the Herman Orientation Function is at least 7% greater than the average level of crystalline orientation of filaments within the segments containing said interlace nodes.

11. The invention as recited in claim 8, wherein the average level of crystalline orientation of filaments within the segments of said yarn between said interlace nodes as measured by the Herman Orientation Function is at least 8% greater than the average level of crystalline orientation of filaments within the segments containing said interlace nodes.

12. The invention as recited in claim 8, wherein the average level of crystalline orientation of filaments within the segments of said yarn between said interlace nodes as measured by the Herman Orientation Function is at least 9% greater than the average level of crystalline orientation of filaments within the segments containing said interlace nodes.

13. The invention as recited in claim 8, wherein said yarn is a multi-filament polyester yarn.

14. A multi-filament yarn comprising a plurality of interlace nodes disposed along the length of said yarn, wherein said yarn is characterized by variable retained heat shrinkage potential at segments along its length such that segments of said yarn containing said interlace nodes have a retained heat shinkage potential in excess of segments of said yarn between said interlace nodes such that upon application of uniform heat to said yarn, the segments of said yarn containing said interlace nodes exhibit enhanced shrinkage and self texturing relative to the segments of said yarn between said interlace nodes such that following said application of uniform heat to said yarn, filaments within the segments of said yarn containing said interlace nodes are characterized by an average cross-sectional area at least 1.56 times the average cross-sectional area of yarn filaments in the segments of said yarn between said interlace nodes and such that the average level of crystalline orientation of filaments within the segments of said yarn between said interlace nodes as measured by the Herman Orientation Function is at least 5% greater than the average level of crystalline orientation of filaments within the segments containing said interlace nodes.

15. The invention as recited in claim 14, wherein the average level of crystalline orientation of filaments within the segments of said yarn between said interlace nodes as measured by the Herman Orientation Function is at least 6% greater than the average level of crystalline orientation of filaments within the segments containing said interlace nodes.

16. The invention as recited in claim 14, wherein the average level of crystalline orientation of filaments within the segments of said yarn between said interlace nodes as measured by the Herman Orientation Function is at least 7% greater than the average level of crystalline orientation of filaments within the segments containing said interlace nodes.

17. The invention as recited in claim 14 wherein the average level of crystalline orientation of filaments within the segments of said yarn between said interlace nodes as measured by the Herman Orientation Function is at least 8% greater than the average level of crystalline orientation of filaments within the segments containing said interlace nodes.

18. The invention as recited in claim 14, wherein the average level of crystalline orientation of filaments within the segments of said yarn between said interlace nodes as measured by the Herman Orientation Function is at least 9% greater than the average level of crystalline orientation of filaments within the segments containing said interlace nodes.

19. The invention as recited in claim 14, wherein said yarn is a multi-filament polyester yarn.

20. The invention as recited in claim 14, wherein following said application of uniform heat to said yarn, filaments within the segments of said yarn containing said interlace nodes are characterized by an average cross-sectional area at least 1.56 times the average cross-sectional area of yarn filaments in the segments of said yarn between said interlace nodes.