EP0873438A1

EP0873438A1 - Improvements in and relating to fiber identification

Info

Publication number: EP0873438A1
Application number: EP95936255A
Authority: EP
Inventors: Ismael Antonio Hernandez
Original assignee: EI Du Pont de Nemours and Co
Current assignee: EIDP Inc
Priority date: 1993-02-16
Filing date: 1995-10-12
Publication date: 1998-10-28
Also published as: AU3827095A; WO1997013895A1; JPH11513447A; EP0873438A4

Abstract

Fiberfill and/or multi-void fibers are identified and/or differentiated by one or more voids being partially filled with a differentiating characteristic that is a protuberance of characterizing polymer material. This material may be the same or different from that of the rest of the fiber. The protuberance is provided by appropriate adjustment of the spinning capillary, i.e., during extrusion to form the fiber.

Description

IHLE

Improvements In And Relating To Fiber Identification

This invention concerns improvements in and relating to fiber identification, and includes a novel method of making a multi-void fiber with a characteristic by which it can later be identified, novel multi-void fibers so marked as to be identifiable, and products and materials including such marked fibers, especially fiberfill filling materials (often referred to shortly as "fiberfill") and products, including batts, fiberballs and other products comprising such marked fibers and materials comprising them, and processes and apparatus for obtaining such multi-void fibers and their products and materials.

A fiber manufacturer's customers demand consistency in performance from the fibers provided by the manufacturer. In other words, the manufacturer's customers require that the properties of any particular fiber not vary appreciably from batch to batch of that fiber as the different batches of that fiber are produced over several years. The fiber manufacturer, however, has a need to be able to identify fiber from different production batches, while maintaining the consistency and uniformity that the customers require. Much notoriety has been given to fiber identification in criminology, for example, as a way to bring murderers or other criminals to justice. Manufacturers also, however, have other more mundane and practical reasons for needing to identify the production batch of particular fibers. So it has long been desirable to find a cheap yet effective system for identifying fibers. Previously, for instance, one method has been to add a chemical or nuclear marker to the fiber, but this method has added expense and complications and has had disadvantages, such as the ease with which some one other than the fiber manufacturer can add the same marker, after manufacture, and so confuse this system for identification.

In particular, there has long existed a need for an economical way to identify and differentiate resilient multi-void fibers (especially polyester multi- void fibers) that are crimped and used as fiberfill in products such as batts, fiberballs and other filling materials and filled articles, such as pillows, filled apparel, comforters, cushions and such like bedding and furnishing material. As indicated, it is important that any identifier system should not change the performance and properties ofthe fibers. Examples of such crimped multi-void resilient filling fibers include those disclosed by Champaneria et al in U. S. Patent No. 3,745,061, and in EP A2 0 067 684 (Jones et al), having 4 voids (sometimes referred to as holes) with a solid axial core, and by Broaddus in U. S. Patent No. 5,104,725, having 7 or more voids, arranged with a central void and other voids arranged around the central void. Both 4-void and 7-void polyester filling fibers have been produced and sold commercially, and have been used as fiberfill. Broaddus compared properties of fiberfill comprising his 7-void filling fibers with those of fiberfill comprising prior commercial 4- void filling fibers and also with those of fiberfill comprising hollow filling fibers. The most important properties to compare for use as fiberfill are the bulk properties; measurement of bulk properties (referred to as TBRM for "Total Bulk Range Measurement") have been described, e.g., by Tolliver in U.S. Patent No. 3,772,137, and so have frictional properties (that were also measured by Broaddus and are also important for fiberfill). Both of these crimped multi-void filling fibers have shown significant advantages over resilient crimped hollow filling fibers (such as disclosed by Tolliver in U. S. Patent No. 3,772,137) in their performance as filling materials. especially when such multi-void filling fibers have had a smooth round peripheral surface. The disclosure of each ofthe above patent specifications is expressly included herein by reference. In addition, multi- void filling fibers with a smooth round peripheral surface and with only three longitudinal voids, are disclosed by Hernandez et al. in U.S. Patent No. 5,458,971 (DP-6320), the disclosure of which is also included herein, by reference.

The present invention solves this need to identify and differentiate multi-void fibers by providing a visual identifying marker in the configuration of the cross-section ofthe multi-void fiber. This marker identifies the multi-void fiber only visually, i.e., without significantly affecting performance ofthe fiber. Fibers with such a visual identifying marker according to the present invention are often referred to herein as "identifier fibers" (or "identifier filaments"). The terms "fiber" and "filament" are often used herein inclusively, without intending that use of one term should exclude the other.

Accordingly, this invention provides a process for preparing multi- void filaments of a synthetic polymer, comprising the steps of post-coalescence melt-spinning the synthetic polymer through segmented spinning capillary orifices so the resulting freshly-spun molten streams coalesce and form continuous filaments having at least three voids, and quenching to solidify the filaments, and, if desired, drawing the resultant solid filaments, and/or further processing, and/or converting to staple fiber, characterized in that molten polymer is also spun in small amount through one or more separate small orifices located so as to form, respectively, one or more small protuberances that are visually identifiable on an inside surface of, respectively, one or more voids ofthe multi-void filaments. There is also provided, as a new article, a multi-void synthetic polymer fiber, having at least three continuous longitudinal voids, wherein the multi -void cross-section ofthe fiber shows characteristic polymer material that protrudes into one or more ofthe voids from an inside surface ofthe void or voids; in other words, the cross-section shows that one or more such void is partially filled with characteristic polymer material that protrudes from a wall into such partially-filled void; thus said characteristic protruding polymer material differentially identifies said fiber from similar multi-void synthetic polymer fibers that do not contain any such protruding polymer material usually but does not significantly differentiate the performance properties of said fiber from said similar fibers. According to a further aspect, this invention provides fiberfill filling material, and articles comprising such material, comprising resilient crimped multi-void filling fibers that are of a synthetic polymer, wherein said multi-void filling fibers have at least three continuous voids throughout their fiber length, and wherein said fiberfill filling material is identified by all or a predetermined proportion of said fibers having a multi-void cross-section that shows characteristic polymer material that protrudes into a predetermined number and predetermined pattern ofthe voids from an inside surface ofthe void or voids.

According to other aspects disclosed herein, fiberfill (and including filled articles thereof) is provided wherein said fiberfill comprises resilient crimped multi-void filling fibers of synthetic polymer, and wherein, e.g., at least 10 percent by weight of said fibers have a multi-void cross-section which shows that one or more such void contains (i.e., is partially filled with) characteristic protruding polymer material (i.e., that protrudes from an inside surface into such partially-filled void), whereby said characteristic protruding polymer material differentially identifies said fiber from a multi-void synthetic polymer fiber whose multi-void cross-section is similar except that it does not contain any such characteristic protruding polymer material and wherein the bulk properties of said fiber as filling material are essentially similar to the bulk properties of such a multi-void synthetic polymer fiber that is of similar cross-section except that it does not contain any such characteristic protruding polymer material; such multi- void fibers may contain at least three continuous longitudinal voids (i.e., throughout their fiber length), as will be understood.

Polymer material protruding from a surface of a wall of an internal void of a (first) multi-void fiber of a synthetic material is used to identify said (first) multi -void fiber and differentiate it from other multi-void fibers of similar cross-section and having similar bulk properties to those ofthe first (identified and differentiated) multi-void fiber, except, of course, that the other multi-void fibers do not have the polymer material protruding from a surface of a wall of an internal void.

Other aspects include methods, apparatus and products disclosed herein. Prefened features include using polyester polymer as the material for the synthetic polymer ofthe multi-void fiber and/or the characteristic polymer material, and preferably for both, including using the same polyester polymer for both, and using the invention for 4-hole fibers, 7-hole fibers, and/or 3-hole fibers with a smooth round periphery, such as are mentioned in the art and above, especially any such multi-void fibers with only 1 ofthe holes (i.e., voids) partially filled.

In most respects, the fiberfill filling materials and resilient crimped multi-void filling fibers ofthe invention are prepared conventionally by methods known in the art, such as refened to herein. Prefened multi-void filling fibers are prepared from polyester polymers, especially poly(ethylene terephthalate), and this prefened embodiment is described herein more particularly, for convenience, it being understood that appropriate modification can be made by those skilled in the art for other synthetic polymers, such as polyamides or polypropylene, to take account of their differences, e.g., in melting conditions and properties, such as melt viscosity. One such disclosure in the art is Champaneria et al U.S. Patent No. 3,745,061, which discloses multi-void synthetic filaments and a spinneret capillary for spinning such filaments containing four substantially equidimensional and equi-spaced parallel continuous voids from synthetic polymers, including polyesters, in Figure 1 thereof. Figures 1 and 2 ofthe accompanying drawings are magnified (625X) photographs of cross-sections of 4-void filaments, Fig. 1 being of prefened filaments according to the invention, whereas Fig. 2 is of prior art filaments for comparison, as discussed in Example 1.

Figure 3 is an enlarged view of a spinneret capillary, taken looking at the lower face ofthe spinneret, for spinning prefened 4-void filaments ofthe invention as in Fig. 1, 4 and 5.

Figures 4-7 are magnified photographs of cross-sections of 4-void filaments, Figs. 4 and 5 being of prefened filaments according to the invention, whereas Figs. 6 and 7 are of prior art filaments for comparison. Figs. 4 and 7 are of magnification 500X. Figs. 5 and 6 are of magnification 1000X. These are discussed in Example 3.

Figure 8 is a graph plotting TBRM data, heights in inches versus pressures in psi, as discussed also in Example 3. Figure 9 is an enlarged view of a spinneret capillary, taken looking at the lower face ofthe spinneret, for spinning prefened 3-void filaments ofthe invention as in Figs. 10 and 11.

Figures 10-13 are magnified photographs of cross-sections of 3-void filaments, Figs. 10 and 1 1 being of prefened identifier filaments according to the invention, whereas Figs. 12 and 13 are of filaments without identifier, for comparison. Figs. 10 and 12 are of magnification 500X. Figs. 11 and 13 are of magnification 1000X. These are discussed in Example 4.

Figure 14 is a graph plotting TBRM data, heights in inches versus pressure in psi, as discussed also in Example 4.

Figures 15 and 16 are magnified photographs showing not only cross- sections of prefened fibers ofthe invention, but also that the fibers are crimped, as described later herein.

Referring to Figure 3 ofthe accompanying drawings, showing an enlarged view of a spinneret capillary for spinning 4-void identifier filaments of the present invention, the similarity to that of Figure 1 of Champaneria will be noted. The capillary is formed of four individual segments designated generally 11, 12, 13 and 14 in the form of T-shaped slots with four radial slots 15, 16, 17 and 18 radiating outwards to join outer peripheral slots 19, 20, 21, 22 that are curved to form arcs of an incomplete circle. At each end of each peripheral slot, 19, 20, 21 and 22, are enlarged "toes" 23 and 24, 25 and 26, 27 and 28, and 29 and 30, respectively, being enlarged ends of said slot to assist in post-coalescence of the emerging molten polymer to form the desired multi-void solid filament, as is known in the art, such as Tolliver, U. S. Patent No. 3,772,137. An important and novel difference in Figure 3 herein (that differentiates from Figure 1 of

Champaneria) is the provision of an orifice 40. Molten polymer extruded through orifice 40 solidifies and coalesces on an internal wall of one ofthe voids of the filament formed by post-coalescence of molten polymer extruded through slots 1 1, 12, 13 and 14, to form a protuberance partially filling one ofthe voids. The relative location ofthe protuberance within the void may vary along a length of the filament, as will be understood.

Magnified cross-sections of such identifier filaments ofthe invention, containing 4 voids, one of which is partially filled with polymer that protrudes from an internal wall of such void, are shown in Figure 1 , at 625X magnification. In contrast, similarly magnified cross-sections of conventional 4-void filaments are shown in Figure 2. As mentioned, the cross-sections in Figs. 1 and 2 have been greatly magnified. Fiberfill filaments are so fine that, without magnification, it is doubtful that anyone would be able to see any void in the cross-section, or whether the filament is solid, hollow, or multi-void, let alone be able to recognize if any void is partially filled with protruding polymer.

As may be seen from Examples hereinafter, both types of filaments can be prepared to have comparable performance and properties as filling materials. In other words, an objective has been achieved in this respect. This will be discussed more hereinafter.

To summarize this point, without preparing and examining greatly- magnified carefully-cut cross-sections and comparing the filaments, most people would be unable to determine significant difference between filaments ofthe invention and conventional filaments ofthe art. So the objective ofthe invention has been achieved economically by use of a different spinneret capillary to give the filament a different cross-sectional configuration internally, without affecting the exterior ofthe filament or its performance, i.e., wherein the difference can only be determined visually, after examining a greatly-magnified carefully-cut cross-section of the filament.

As will readily be understood, the invention lends itself to many variations. For instance the number and pattern ofthe protuberances in relation to the voids may be varied, especially with filaments having larger numbers of voids, such as 7 voids, bearing in mind that it has generally been thought desirable to maximize the void content to take advantage ofthe presence ofthe voids. It will generally be desirable for the protuberance to fill about 25 to about 50% ofthe volume ofthe void, and generally to extend to an amount of about 25 to 50% of the average web thickness ofthe filament between adjacent voids, bearing in mind the above, and the objective of having a characteristic that is relatively easy to detect visually, especially when using the same polymer material. It is not necessary to provide every filament (i.e., 100%) with identifier, but a regulated (i.e., predetermined) proportion (e.g., at least about 10% by weight) of particularly-identified filaments may be included, and recorded, for a batch of fiber that is sold. Furthermore, although it is less costly, so generally prefened, to spin filaments from a single polymer, so the polymer material is the same in the protuberance as in the rest ofthe filament, different polymers may be used, if desired, so as to provide better identification for merges or batches of fiber. In other words, fiberfill (one or more batches) according to the invention can be identified by providing a predetermined proportion (that may be recorded, and may vary up to 100%) ofthe constituent filling fibers with a predetermined number and predetermined pattern of voids containing visual identifier, i.e., characteristic polymer material protruding into, i.e., partially filling, such void(s), as described, and these details may all be recorded. As mentioned above, and as demonstrated in the Examples, partially filling one or more voids ofthe multi-void filling fibers (according to the invention) did not significantly change the bulk properties or performance ofthe fibers as fiberfill. Applicant has also found that the extent to which the voids are filled has not significantly changed the bulk properties or performance. So long as all the voids remain to some degree, the bulk performance properties have not been significantly affected. This is different from what has been taught in the art for hollow fibers. So this was a new and surprising finding. In other words, partially filling one or more voids in a multi-void filling fiber (according to the invention) has not been found to affect the bulking properties ofthe multi-void filling fibers, whereas the art has taught that extruding extra polymer so it coalesces onto the internal surface of a hollow filament will change the bulkiness of the resulting hollow filament. In contrast to hollow fibers, it seems that it is the presence of the particular number of voids, located symmetrically or regularly around the cross-section ofthe multi-void fiber, rather than the relative sizes of the various voids in the cross-section, that determines the bulkiness.

The invention is further illustrated in the following Examples, all parts and percentages being by weight, unless otherwise indicated. The levels of coatings (slickeners and finishes) applied to the filaments were OWF (with regard to the weight ofthe fiber). Relative Viscosity (sometimes refened to as LRV) and void content (by volume, by a flotation method) were determined by the methods refened to in U.S. Patent No. 4,712,988 (Broaddus et al.). Bulk measurements were determined by the method refened to in Tolliver U.S. Patent No. 3,772,137 refened to hereinabove, and crimp measurements essentially as described therein. Fiber-to-fiber friction values for fiberfill filling (staple) fibers are generally obtained by what is known as Staple Pad Friction (SPF) measurements.

As used herein, a staple pad of the fibers whose friction is to be measured is sandwiched between a weight on top of the staple pad and a base that is underneath the staple pad and is mounted on the lower crosshead of an Instron 1122 machine (product of Instron Engineering Corp. , Canton, Mass).

The staple pad is prepared by carding the staple fibers (using a SACO- Lowell roller top card) to form a batt which is cut into sections, that are 4.0 ins in length and 2.5 ins wide, with the fibers oriented in the length dimension of the batt. Enough sections are stacked up so the staple pad weighs 1.5 g. The weight on top of the staple pad is of length (L) 1.88 ins, width (W) 1.52 ins, and height (H) 1.46 ins, and weighs 496 gm. The surfaces of the weight and of the base that contact the staple pad are covered with Emery cloth (grit being in 220 to 240 range), so that it is the Emery cloth that makes contact with the surfaces of the staple pad. The staple pad is placed on the base. The weight is placed on the middle of the pad. A nylon monofil line is attached to one of the smaller vertical (WxH) faces of the weight and passed around a small pulley up to the upper crosshead of the Instron, making a 90 degree wrap angle around the pulley.

A computer interfaced to the Instron is given a signal to start the test. The lower crosshead of the Instron is moved down at a speed of 12.5 in/min. The staple pad, the weight and the pulley are also moved down with the base, which is mounted on the lower crosshead. Tension increases in the nylon monofil as it is stretched between the weight, which is moving down, and the upper crosshead, which remains stationary. Tension is applied to the weight in a horizontal direction, which is the direction of orientation of the fibers in the staple pad. Initially, there is little or no movement within the staple pad. The force applied to the upper crosshead of the Instron is monitored by a load cell and increases to a threshold level, when the fibers in the pad start moving past each other. (Because of the Emery cloth at the interfaces with the staple pad, there is little relative motion at these interfaces; essentially any motion results from fibers within the staple pad moving past each other.) The threshold level indicates what is required to overcome the fiber-to-fiber static friction and is recorded.

The coefficient of friction is determined by dividing the measured threshold force by the 496 gm weight. Eight values are used to compute the average SPF. These eight values are obtained by making four determinations on each of two staple pad samples.

EXAMPLE 1

Filaments were spun from poly(ethylene terephthalate) of relative viscosity (LRV) 20.4, at a polymer temperature of 291-297°C, at 1195 ypm (1092 mpm), through a spinneret with 388 capillaries, at a throughput per capillary of 0.234 lbs./hr. (0.106 kg./hr.), using capillary orifice designs as shown in Figure 3. The spun filaments were assembled to form a rope of 922,000 relaxed drawn denier. The rope was drawn in a conventional manner, using a draw ratio of 3.39X in a hot, wet spray draw zone maintained at 90°C. The drawn filaments were crimped to three different levels, i.e., to obtain three different levels of crimp, and conespondingly of bulkiness (namely, Support Bulk (i.e., bulk at 0.2 psi) heights of 0.6, 0.8 and 0.9 inches measured on a stack of carded webs, as described by Tolliver), in a conventional stuffer box crimper of cantilever type (3.5 in, 8.9 cm size), and the crimped ropes were relaxed in an oven at 180°C before cutting. A conventional antistatic overlay finish of about 0.07% by weight was applied to every sample. The first (lowest bulk) fiber had, however, also been slickened before relaxing with a finish containing about 1% silicone per weight of fiber. The resulting filaments were all cut to staple of length 2 inches (5.4 cm). Cross sections ofthe resulting cut fibers of the invention are shown in Figure 1, and show a solid axial core and four parallel continuous internal voids, one of which contains a protuberance on an inside surface of the void to serve as an identification mark. The outside peripheries ofthe fibers were round and smooth. The fibers were found to have an average void content of 17.1 % and a denier per filament of about 5.5.

For comparison, these Samples of fibers ofthe invention were compared with cunent conventional 4-void fibers, of average void content 15.5%, crimped to similar levels of crimp (providing similar Support Bulk levels), ofthe same denier and which were made similarly, except for using a capillary similar to that of Figure 3, herein, but without any orifice 40 for an identifier, in other words, similar to that in Figure 1 of Champaneria, as discussed above. The cross- sections of these conventional fibers were similar to those ofthe invention (Figure 1) except that all four voids were clear, i.e., there were no protuberances that act as identifier marks as shown in Figure 1.

As indicated, the performance and properties ofthe two sets of fibers as fiberfill filling material were compared and found to be essentially similar, i.e., the bulkiness of each pair ofthe fiberfill samples was found to be similar, despite the differences in cross-section ofthe fibers. The friction measurements ofthe slickened fibers were, respectively, 0.265 and 0.293, i.e., essentially similar.

EXAMPLE 2

Two types of fibers (one according to the invention, with an identifier, and the other of conventional cross-section, without such identifier) were prepared essentially as described in Example 1, except that they were spun through spinnerets having 212 capillaries, and were of higher density. The void contents of the filaments, as drawn, were about 17.9% and 19.8%, respectively, and the relaxed drawn deniers were about 14.4 and 14.3, respectively, for the fiber ofthe invention (having the identifier) and the conventional fiber. The properties of both types of fibers were again compared and both fibers were found to have essentially the same properties, and the same performance as fiberfill. EXAMPLE 3

Filaments were spun from poly(ethylene terephthalate) of relative viscosity (LRV) 20.4, at a polymer temperature of 291-297°C at 1277 ypm (1 167 mpm), through a spinneret with 363 capillaries, at a throughput per capillary of 0.278 lbs./hr. (0.126 kg./hr.), using capillary orifice designs as shown in Figure 3 herein. The spun filaments were assembled to form a rope of 65,000 relaxed drawn denier. The rope was drawn in a conventional manner, using a draw ratio of 2.9X in a hot, wet spray draw zone maintained at 95 °C. The drawn filaments were crimped to two different levels, to obtain two levels of crimp (and conespondingly two levels of bulkiness, namely Support Bulk, measured as described by Tolliver for carded webs in U.S. Patent 3,772,137), as given for Sample A and for Sample C in TABLE A below, in a conventional stuffer box crimper of cantilever type (1.0 in, 2.5 cm size) and the crimped ropes were relaxed in an oven at 180°C before cutting. A conventional antistatic overlay finish of about 0.15% per weight was applied to every sample. The resulting filaments were all cut to staple of length 2 inches (5.4 cm).

Cross-sections of the resulting cut identifier fibers are shown in Figures 4 and 5. Each such filament contains a solid axial core and four parallel continuous voids, one of which contains a protuberance of an inside surface ofthe void to serve as an identification mark. These fibers have a void content of about 12.5%.

The above fibers were compared with cunent conventional 4-void fibers (crimped to similar levels of crimp, providing similar levels of bulkiness, as described above, as given for Sample B and for Sample D in TABLE A), ofthe same denier and which were made similarly, except for using a conventional capillary (without orifice 40, in other words, similar to Figure 1 of Champaneria as discussed above). These conventional fibers are shown in Figures 6 and 7. These cross-sections were similar to those ofthe invention, except that they contain no fiber identification marker, i.e., there are no protuberances that act as identifier marks as shown in Figures 4 and 5.

Sample A (identifier fibers) and Sample B (conventional fibers) were crimped to similar crimp levels of about 4.5 crimps per inch (CPI), and a Crimp Index (CHI) of about 7. Table A shows that the TBRM data measured for such Samples are very similar, so much so that, when the data are plotted on a graph, as shown in Figure 8, Curves A and B are virtually indistinguishable. Similarly, Sample C (identified fibers) and Sample D (conventional fibers) were crimped to similar crimp levels of about 7 crimps per inch (CPI), and to a similar Crimp Index (CHI) of about 1 1, and give similar TBRM results (see Table A and Figure 8). In other words, when these two types of fibers are crimped to similar crimp levels (similar CPI and CHI), the resulting bulkiness of the fibers (as measured by TBRM) is almost the same, despite the differences in their cross-sections, which are visible in magnified photographs, as shown in Figures 4 to 7.

TABLE A

Pressure Height (inches under such Pressure (psi) Sample A Sample B Sample C Sample D 0.001 5.930 5.944 5.295 5.31 1 0.005 4.316 4.387 3.816 3.855

0.010 3.370 3.425 3.098 3.132 0.040 1.588 1.609 1.869 1.879 0.20 0.500 0.527 0.813 0.822

As indicated hereinabove, a 3-void filling fiber with a smooth round peripheral surface is disclosed by Hernandez et al. in U.S. Patent No. 5,458,971, so the following Example 4 was performed to make 3-void filling fibers with and without identifiers in one ofthe voids, and to compare their properties and performance as fiberfill. Fig. 9 shows a spinneret capillary for spinning identifier filaments with three voids. It will be noted that the capillary is segmented, with three segments __. disposed symmetrically around an axis or central point £. Each segment _X consists of two slots, namely a peripheral arcuate slot _2 and a radial slot __,, the middle ofthe inside edge of peripheral arcuate slot _2 being joined to the outer end of radial slot __., so each segment forms a kind of "T-shape" with the top ofthe T being curved convexly to form an arc of a circle. Each peripheral arcuate slot _Z extends almost 120 deg. around the circumference ofthe circle. Each radial slot __. comes to a point 5_4_ at its inner end. Points _4 are spaced from the central point Q. Each peripheral arcuate slot _Z is separated from its neighbor by a distance which is refened to as a "tab". The short faces of neighboring peripheral arcuate slots _Z on either side of each tab are parallel to each other and parallel to the radius that bisects such tab. In many respects, the capillary design shown in Figure 9 is typical of designs used in the art to provide hollow filaments by post-coalescence spinning through segmented orifices. Points _ at the inner ends of radial slots __. are provided in the spinneret capillary design shown in Fig. 9, however, to improve coalescence ofthe polymer at the center ofthe filament, i.e., to ensure that the three voids do not become connected. An important and novel difference in Figure 9 herein (that differentiates from orifice designs of the prior art) is the provision of an orifice 60. Molten polymer extruded through orifice 60 solidifies and coalesces on an internal wall of one ofthe voids ofthe filament formed by post-coalescence of molten polymer extruded through slots 51, 52 and 53 to form a protuberance partially filling one ofthe voids and acting as an identifier when the cross-section of that filament is examined under magnification. The relative location ofthe identifier protuberance within the void may vary along a length ofthe filament, as will be understood. Also, as may be understood and as has already been explained for multi-void fibers containing more than three voids, the invention lends itself to many variations. For example, more than one void may be partially filled by providing, conespondingly, more than one orifice like orifice 60.

EXAMPLE 4

Filaments were spun from poly(ethylene terephthalate) of relative viscosity (LRV) 20.4, at a polymer temperature of 291 -297°C at 1277 ypm (1 167 mpm), through a spinneret with 363 capillaries, at a throughput per capillary of 0.278 lbs./hr. (0.126 kg./hr.), using capillary orifice designs as shown in Figure 9. The spun filaments were assembled to form a rope of 65,000 relaxed drawn denier. The rope was drawn in a conventional manner, using a draw ratio of 2.9X in a hot, wet spray draw zone maintained at 95°C. The drawn filaments were crimped to two different levels, to obtain two levels of crimp (and conespondingly two levels of bulkiness, namely Support Bulk, measured as described by Tolliver for carded webs in U.S. Patent 3,772,137, as given for Sample A and for Sample C in TABLE B below), in a conventional sniffer box crimper of cantilever type (1.0 in, 2.5 cm size) and the crimped ropes were relaxed in an oven at 180°C before cutting. A conventional antistatic overlay finish of about 0.15% per weight was applied to every sample. The resulting filaments were all cut to staple of length 2 inches (5.4 cm).

Cross-sections ofthe resulting cut identifier fibers are shown in Figures 10 and 1 1. Each such filament contains a solid axial core and three parallel continuous voids, one of which contains a protuberance of an inside surface ofthe void to serve as an identification mark. These fibers have a void content of about 18%.

The above fibers were compared with 3-void comparison fibers (crimped to similar levels of crimp, providing similar levels of bulkiness, as described above, as given for Sample B and for Sample D in TABLE B), ofthe same denier and which were made similarly, except for using a capillary without any extra orifice 60, i.e., a capillary as described and illustrated in Fig. 2 of aforesaid U.S. Patent No. 5,458,971. These comparison fibers are shown in Figures 12 and 13, and their cross-sections are similar to those ofthe invention, except that they contain no fiber identification marker, i.e., there are no protuberances that act as identifier marks as shown in Figures 10 and 1 1. Sample A (identified fibers) and Sample B (comparison fibers) were crimped to similar crimp levels of about 4.5 crimps per inch (CPI), and to a Crimp Index (CHI) of about 7. Table B shows that the TBRM data measured for such Samples are very similar, so much so that, when the data points are plotted on a graph, as shown in Figure 14, Curves A and B are extremely close together. Similarly, Sample C (identified fibers) and Sample D (conventional fibers) were crimped to similar crimp levels of about 7.5 crimps per inch (CPI), and to a similar Crimp Index (CHI) of about 11, and give similar TBRM results (see Table B and Figure 14). In other words, when these two types of fibers are crimped to similar crimp levels (similar CPI and CHI), the resulting bulkiness ofthe fibers (as measured by TBRM) is virtually indistinguishable, despite the differences in their cross-sections, which are visible in magnified photographs, as shown in Figures 10 to 13.

TABLE B

Pressure Heisht (inches) under such Pressure (psi) Sample A Sample B Sample C Sample D 0.001 5.873 5.925 5.46 5.419 0.005 4.412 4.419 3.932 4.006 0.010 3.497 3.473 3.208 3.251

0.040 1.694 1.643 1.952 1.972 0.20 0.535 0.550 0.861 0.861

In all the above comparative tests, where the bulkiness of fiberfill comprising identifier fibers ofthe invention was compared with the bulkiness of fiberfill comprising fibers of similar cross-section except that all voids were clear (i.e., without identifier), the crimping of each set of fibers that were compared was carried out in the same stuffer-box machine under the same conditions (using the same velocity, temperature profile and pressures). Figure 15 is a magnified photograph of crimped 4- void fibers according to the invention, showing some 4- void cross-sections somewhat similarly to those in the (magnified) photographs in Figs. 1, 4, and 5, except that more ofthe fiber can be seen so this photograph can show that these fibers have indeed been crimped conventionally, using such a stuffer-box. Similarly, Figure 16 is a (magnified) photograph like that in Figure 15, except of crimped 3-void fibers according to the invention.

The multi-void fibers ofthe invention may be processed into products such as batts and fiberballs (sometimes refened to as clusters) and further processed into pillows, filled apparel, comforters, cushions and like bedding and furnishing material, as disclosed in the art, including that specifically mentioned herein, and art such as LeVan U. S. Patent Nos. 3,510,888, and 4,999,232, and various Marcus patents, including U. S. Patent Nos. 4,618,531, 4,783,364, 4,794,038, 4,818,599, 4,940,502, and 5,169,580, and U. S. Patent No. 5,088,140 (Belcher et al). Although, hitherto, most fiberfill has comprised cut fiber, such as has been disclosed above, there has been growing commercial interest in using deregistered tows of continuous filaments as fiberfill, as disclosed for example by Watson in U. S. Patent Nos. 3,952,134 and 3,328,850. Accordingly, application ofthe invention to fiberfill in the form of deregistered tows of continuous filaments is also contemplated herein, and the invention is not confined to cut fibers nor to fiberfill comprising such cut fibers. Additionally, as well understood in the art, it has been commonplace to mix or blend fibers for use as filling material. Accordingly, it is contemplated that fiberfill according to the invention may consist essentially entirely of identifier fibers according to the invention, or these identifier fibers may be mixed with other fibers; thus, the fiberfill filling material may be identified by all or a portion of its fibers being such identifier fibers. Reference is made in this regard to my copending application No.

(DP-471 1-D), being filed simultaneously herewith, the disclosures of which is hereby expressly included herein by reference, and which solves the problem of identifying and differentiating hollow filling fibers (containing a single continuous void throughout their fiber length) and fiberfill comprising such filling fibers. Fiberfill, as is well understood by those skilled in the art, is shorthand for fiberfill filling material, or more shortly fiberfilling material, and refers to a bulky mass of fibers used to fill articles, such as pillows, cushions and other furnishing materials, including other bedding materials, such as sleeping bags, mattress pads, quilts, comforters, duvets and the like, and in apparel, such as parkas and other insulated articles of apparel, whether quilted or not. Crimp is an important characteristic and provides the bulk that is an essential requirement for fiberfill. Generally, the fibers are crimped by mechanical means, usually in a stuffer-box crimper, as described, for example, in Halm et al. in USP 5,112,684. Crimp can also be provided by other means, such as asymmetric quenching or using bicomponent filaments as reported, for example, by Marcus in USP 4,618,531 and in USP 4,794,038, and in the literature refened to therein, so as to provide "spiral crimp". All this is well understood by those skilled in this art.

Claims

We claim:

1. Process for preparing multi-void filaments of a synthetic polymer, comprising the steps of post-coalescence melt-spinning the synthetic polymer through segmented spinning capillary orifices so the resulting freshly-spun molten streams coalesce and form continuous filaments having at least three voids, and quenching to solidify the filaments, and, if desired, drawing the resultant solid filaments, and/or further processing, and/or converting to staple fiber, characterized in that molten polymer is also spun in small amount through one or more separate small orifices located so as to form, respectively, one or more small protuberances that are visually identifiable on an inside surface of, respectively, one or more voids ofthe multi-void filaments.

2. A process according to Claim 1, wherein said synthetic polymer is a polyester.

3. A process according to Claim 1 or 2, wherein said molten polymer is also a polyester.

4. Articles that are multi-void fibers of a synthetic polymer and having at least three continuous voids throughout their fiber length, and a multi- void cross-section that shows characteristic polymer material that protrudes into one or more ofthe voids from an inside surface ofthe void or voids.

5. Articles that comprise fiberfill filling material comprising resilient crimped multi-void filling fibers that are of a synthetic polymer wherein said multi-void filling fibers have at least three continuous voids throughout their fiber length, and wherein said fiberfill filling material is identified by all or a predetermined proportion of said fibers having a multi-void cross-section that shows characteristic polymer material that protrudes into a predetermined number and predetermined pattern of the voids from an inside surface ofthe void or voids.

6. Articles according to Claim 4 or 5, wherein said synthetic polymer is a polyester.

7. Articles according to Claim 4 or 5, wherein said synthetic polymer is a polyester, and wherein said characteristic polymer material is also a polyester.