US3676991A

US3676991A - Crimped discontinuous filaments

Info

Publication number: US3676991A
Authority: US
Inventors: Hugh J Fairfield
Original assignee: DuPont Canada Inc
Priority date: 1969-11-06
Filing date: 1969-11-06
Publication date: 1972-07-18
Anticipated expiration: 1989-07-18

Abstract

A method of converting a mass of textile filaments in the form of textile material waste, tangled thread waste or cold-drawable continuous filaments of a synthetic polymer, to a useful product by forwarding the mass at a low speed under a restrained condition, while withdrawing the mass at a high speed to separate, randomly stretch and cool the filaments. The filaments are then collected. When the initial material is undrawn colddrawable continuous filaments of a synthetic polymer, the resulting product is a mass of novel discontinuous drawn filaments having variable lengths, undrawn segments randomly spaced along the lengths, and crimps in the filaments in random directions spaced randomly along the lengths.

Description

United States Patent Fairfield [S4] CRIMPED DISCONTINUOUS FILAMENTS Hugh J. Fairfield, Galt, Ontario, Canada Du Pont of Canada Limited, Montreal, Quebec, Canada [22] Filed: 7 Nov. 6, 1969 [21] Appl. No.: 874,589

Related U.S. Application Data [63] Continuation-impart of Ser. No. 751,272, Aug. 8, 1968, abandoned, which is a continuation-in-part of Ser. No. 597,263, Nov. 28, 1966, abandoned.

[72] Inventor:

[73] Assignee:

[56] References Cited UNITED STATES PATENTS 2,370,112 2/1945 Truitt ..l61/173 [451 July 18,1972

3,212,158 10/1965 Kasey,.lr. ..l6l/l79 Primary Examiner-Robert F. Burnett Assistant Examiner-Linda Koeckert AttorneyWilliam C. McCallum [57] ABSTRACT A method of converting a mass of textile filaments in the form of textile material waste, tangled thread waste or cold-drawable continuous filaments of a synthetic polymer, to a useful product by forwarding the mass at a low speed under a restrained condition, while withdrawing the mass at a high speed to separate, randomly stretch and cool the filaments. The filaments are then collected. When the initial material is undrawn cold-drawable continuous filaments of a synthetic polymer, the resulting product is a mass of novel discontinuous drawn filaments having variable lengths, undrawn segments randomly spaced along the lengths, and crimps in the filaments in random directions spaced randomly along the lengths.

11 Claims, 6 Drawing Figures PATENTED JUL 1 8 m2 SHEET 1 OF 3 INVENTOR Hugh J. FAIRFIELD P'A TENT AGENT mamenauumn 3.676391 SHEET 3 BF 3 INVENTOR Hugh J. FAIRFIELD PATENT AGENT CRIMPED DISCONTINUOUS FILAMENTS CROSS REFERENCES TO RELATED APPLICATIONS This application is a continuation-in-part of copending application Ser. No. 751,272 filed Aug. 8, 1968, now abandoned, which application was a continuation-in-part of then copending application Ser. No. 597,263 filed Nov. 28, 1966 and now abandoned.

FIELD OF THE INVENTION This invention relates to a method of converting a mass of textile filaments in the form of textile material waste, tangled thread waste or cold-drawable continuous filaments of a synthetic polymer to a useful product. More particularly this invention relates to discontinuous filaments in a novel form and having novel properties made from undrawn cold-drawable continuous filaments of synthetic polymers.

By the term cold-drawable is meant filaments of any synthetic polymer which may be oriented by cold-drawing" as defined by Carothers in US. Pat. No. 2,071,250. Suitable types of polymers include polyamides, polyesters, polyethers, polyethylenes and polypropylenes. Furthermore, this invention relates to a process for converting undrawn or partially drawn waste material of cold-drawable synthetic polymer filaments to a novel product. I

DESCRIPTION OF THE PRIOR ART One of the paradoxes of the textile industry is the production of continuous filament yarns, which are then cut to form fibers of various staple lengths that must then be realigned into attenuated strands to form a useable yarn. Staple fibers made from continuous filament yarns may possess superb physical properties but if the fibers cannot be processed satisfactorily they are practically worthless for textile uses. Natural fibers such as cotton and wool have a spiral deformation or crimp somewhat like a cork screw. The crimp however although appearing uniform in one filament, tends to be random from one filament to another. Thus when the natural fibers are processed into yarn or batts, the crimps in the fibers mix with each other and tend to cling together forming a cohesive product. In preparing staple fibers from continuous filaments it is usually necessary to place an artificial crimp into the fiber so that cohesive properties are obtained when the staple fibers are further processed or blended with natural fibers. This artificial crimp may be inserted either before or after the continuous filament yarn is cut or broken into staple fiber lengths. Throughout the specification the term cohesive means that the fibers by virtue of their construction have a tendency to cling to one another. The crimp in a staple fiber made from a continuous filament yarn may be put in by a number of well known crimping devices, such as nip rolls, stufi'lng box crimpers, twisting and false twisting devices and many others. Many of these devices, however, produce a crimp to a certain regular pattern and there is little or no randomness about the crimp in the fiber. This regular pattern is generally uniform within certain tolerances, e.g., 14:2 crimps per inch or 14:4 crimps per inch, and the tolerances only represent the maximum deviation from the average fiber crimp. The crimps are uniform in as much as they are similar in shape or formation. It has been found that staple fibers having a random crimp have better cohesive properties when further processed into yarn, batts or the like than fibers having a regular crimp pattern.

There are several well known methods of preparing staple fibers from continuous filament yarns. In one such method, continuous filaments are formed into a tow, the tow may be stretched to draw or orient the filaments, crimped, and then cut or broken into staple lengths by any one of a number of well known staple forming devices. The degree of molecular orientation of the staple fibers so produced is uniform within specified tolerances. In the past it has generally been considered that reasonable uniformity is required for both the crimp and the orientation in a staple fiber made from a continuous filament yarn to ease processing. However, poor cohesion problems can occur when synthetic staple fibers are blended with natural fibers or with other synthetic staple fibers due to limitations imposed by the fiber composition and g the methods available for imposing the crimps. One such problem is the poor openness of staple fiber which leads to shiners" or bundles of married fibers in a finished fabric. It is believed that this problem may to some extent be attributed to the regularity of staple length and regularity of the crimp within the shiner.

The process of the conventional .picking machine which is used in the conversion of thread, knitted, and woven waste material to a fiber form, is more of a grinding process, and as in most grinding processes, a great deal of heat is generated. With natural fibers such as wool and cotton this process works well. If the natural fiber becomes overheated, some of the material burns and chars to an ash which is readily dusted off the remaining fiber, leaving it at worst somewhat discolored but still a useful product. However, with the development of synthetic fibers, the grinding process has not proved successful. It has been found that the heat generated in the machine tends to melt the synthetic fibers, and on cooling, the fibers fuse together into a mass which of course renders them useless.

In the preparation of continuous filament yarns such as nylon, polyester, polypropylene and many others a vast annual poundage of both drawn and undrawn waste is produced, and there is presently no commercially feasible process by which undrawn fiber waste may be processed to a useful textile product, although the waste may be pelletized and used for molding powder. In certain cases the undrawn fiber waste can be remelted or dissolved for respinning, however, in many instances this is not carried out, mainly for economic reasons, and if the waste cannot be used in its existing form, it must be discarded or destroyed.

- SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of converting a mass of textile filaments in any of a number of waste and other forms into a useful product. It is a further object of the present invention to produce a novel product from undrawn cold-drawable continuous filaments of a synthetic polymer. A further object of the present invention is to produce a mass of novel discontinuous filaments having good cohesive properties and good blending properties with natural fibers and other synthetic fibers.

With these and other objects in view there is provided a method of converting a mass of textile filaments selected from the group consisting of: textile material waste, tangled thread waste and cold-drawable continuous filaments of a synthetic polymer, to a useful product comprising the steps of: forwarding the mass at a low speed under a restrained condition, withdrawing said mass at a high speed to separate and stretch the filaments in a random manner and at the same time cooling the filaments, and collecting the resulting product.

Furthermore, there is provided a mass of discontinuous filaments of a cold-drawable synthetic polymer having randomly distributed variable lengths, the filaments being cold-drawn but having undrawn segments randomly spaced along the lengths, and crimps in the filaments in random directions spaced randomly along the lengths.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects and advantages of this invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a diagrammatic side view illustrating a mass of textile filaments being converted according to an embodiment of the present invention.

FIG. 2 is a perspective representation of the conversion machine shown in FIG. 1.

FIG. 3 is an enlarged fragmentary perspective representation of one of the staves of the machine shown in FIG. 2.

FIG. 4 is a diagrammatic side view illustrating one embodiment of a driving means for the feed assembly and cylinder of the machine shown in FIG. 2.

FIG. 5 is a diagrammatic side view illustrating a further embodiment of the conversion process of FIG. 1 wherein steam is applied to the mass of textile filaments.

FIG. 6 is a sketch showing two discontinuous filaments of this invention.

DETAILED DESCRIPTION OF INVENTION Referring now to the drawings, in which similar reference characters denote like parts throughout, the initial material, referred to as (A) in FIG. 1, may be a mass of textile fibers such as undrawn or partially drawn continuous filaments of synthetic polymers which are cold-drawable and may be in a tangled or random form. Undrawn continuous filaments in this context include partially drawn continuous filaments that have large undrawn segments along their length, or filaments that when converted by the process of this invention produce drawn discontinuous filaments having undrawn segments randomly spaced along their lengths. Continuous filaments in this context refer to filaments that have been spun continuously but need not be in a continuous form when processed according to this invention. Waste filaments that have been cut from a bobbin of continuously spun filaments may be processed by this method provided the cut filaments are long enough to be held between the forwarding and withdrawing means. Continuous filaments may include bi-component filaments, cospun filaments, filaments from copolymers and filaments having varying cross-sections including trilobal shapes and dog bone shapes. The synthetic polymers may include polyester, polypropylene, nylon, polyvinyl alcohol, polyvinyl chloride and others. Nylon includes polyhexamethylene adipamide (nylon 66) and polycaprolactam (nylon 6). Polyester includes polyethylene terephthalate.

The mass of textile fibers may also be made from drawn continuous filaments of cold-drawable synthetic polymers in the form of waste yarn, or a knitted, woven or non-woven waste. The mass may be wholly a synthetic fiber of one or more types or partly a synthetic fiber with a natural fiber such as wool or cotton.

The initial material, hereinafter referred to as the material is preferably first lubricated by an antistatic or fiber lubricating agent or an emulsion of both. This lubrication may be carried out in several different ways, such as spraying a batch of filaments layer by layer with a desired amount of lubricating agent or by an air pressure spray nozzle system (not shown). set up over the feed apron 10 of the conversion machine. In the latter case the antistatic lubricating agent is sprayed on the material in the desired quantity as it passes under the nozzle.

The conversion machine shown in FIGS. 1 and 2 is supported on a mounting structure 11 which may be of any desired form and includes an elongated conveyor or feed apron 10. There are two main features to the machine. Firstly, the essentially cylindrical structure, hereinafter referred to as the cylinder 25, so constructed as to subject a tangled mass of filaments to a segregating and stretching process as it is being released slowly under restraint.

A large volume of air created by the fan-like action of the cylinder 25 passes through the cylinder cooling the filaments being segregated and stretched. As explained more fully hereinafter, the cylinder is rotating at a relatively high speed.

A multitude of needles mounted on the periphery of the cylinder pick up filaments from the restrained tangled mass, and as the needles continue to rotate with the cylinder these filaments are segregated, aligned one to the other and stretched. While being stretched the filaments are pulled to the base of the needles, partly by the position of the needles on the cylinder, and partly by suction caused by the fan-like action of the cylinder. When tight to the base of the needles, combs mounted on the periphery of the cylinder comb the filaments.

The filaments of the material are simultaneously stretched at a high speed and randomly crimped. They are then broken or severed into variable lengths. The second feature is the material feeding and metering means, hereinafter referred to as the feed roll assembly 12, whereby first a set of fluted rolls and then several Garnett wire covered feed rolls meter the material to the cylinder 25 while restraining the cylinder 25 from jerking or pulling the material.

Positioned upon the mounting structure 11 is the feed roll assembly 12 comprising first an upper and lower fluted feed rolls, 13 and 14, which extend transversely across the mounting structure 11 and are located at the end of the feed apron 10 in such a position that the material (A) coming off the feed apron 10 is fed between the two rolls, l3 and 14. The rolls l3 and 14 are journalled to rotate within the conventional housings 15, the upper roll 13 being biased downward by the springs 16. The purpose of these fluted feed rolls is to meter the flow of material through the machine and to ensure that the flow is comparatively even.

The material leaving the fluted feed rolls 13 and 14 is picked up by the lower Garnett wire covered feed roll 17. Garnett wire or metallic clothing as it is sometimes referred to in the trade, is a saw toothed pointed wire. The rolls are spirally grooved around the cylindrical surface. The groove in each roll is preferably one-eighth of an inch deep and spaced from about one-sixteenth to one-fourth of an inch apart depending on the gauge and size of the wire. The Garnett wire fits in the groove in a continuous spiral wound around the roll. The wire may be held tightly in place by deforming the metal on the roll between the grooves so that it grips the wire in the groove. Garnett wire is obtainable in many gauges, and a heavy gauge wire, such as number 10 gauge, is preferred for clothing the rolls in the feed assembly. The teeth on the Garnett wire point in such a way that the material is held and prevented from being pulled or jerked into the cylinder 25. Thus as the feed rolls rotate, the material is metered to the cylinder 25 at a relatively slow rate.

After being collected by the lower roll 17 the material is passed under the first upper Garnett wire covered roll 18 which is journalled to rotate within conventional housings 19. This roll 18 is biased downward by the springs 20. The clearance between the wire tips of the upper roll 18 and the lower roll 17 is in the order of one-sixteenth to one-eighth inch, but if an excessive amount of material moves between these two rolls the upper roll 18 moves up against the springs 20 and the clearance increases. The material then continues on around the circumference of the lower roll 17 and under a second upper Garnett wire covered roll 21 having the same clearance as the first upper roll 18 from the lower roll 17 and journalled to rotate within conventional housings 22. A further Garnett wire covered roll 23 known as a clearing roll is mounted above the second upper roll 21 located such that the clearance between the second upper roll 21 and the clearing roll 23 is approximately one-sixteenth to one-eighth inch. This spacing between roll 21 and roll 23 remains constant, however, the bearing housings are joined together to allow the second upper roll 21 and the clearing roll 23 to move vertically upwards against springs 24, thus the clearance between the second upper roll 21 and the lower roll 17 increases.

There is considerable pull or drag on the material when the filaments are being stretched by the high speed rotation of the cylinder 25. The Garnett wire on the feed rolls 17, 18 and 21 has the teeth pointing in the direction opposite to rotation, so the material is held or restrained by the Garnett wire while this pull is being exerted, and fed to the cylinder 25 as the feed rolls rotate. The clearing roll 23 rotates in the same direction as the second upper roll 21 but has the Garnett wire teeth pointing in the direction of travel for material (A).

All these rolls are driven by a conventional means such as that illustrated in FIG. 4. In this specific embodiment, a 2 HP motor 42 drives the lower roll 17 through a worm gear reduction box 43 and a chain drive 44. The chain sprockets can be changed to vary the feed speed. The lower fluted feed roll 14 is driven by a chain drive 45 from the lower roll 17. There is no direct drive to the upper fluted feed roll 13 which, as shown in FIG. 4, is driven by the meshing of the upper fluted feed roll with the lower fluted feed roll 14, or, as shown in FIG. 1, by the action of the material (A) squeezed between the upper feed roll 13 and the lower feed roll 14. A further chain drive 46 from the lower fluted feed roll 14 drives the feed apron 10. A large gear 47 on the lower roll 17 drives a gear 48 on the first upper Garnett wire covered roll 18 and a gear 49 on the second upper Garnett wire covered roll 21. The clearing roll 23 is driven from a chain drive 50 from the second upper Garnett wire covered roll 21.

The peripheral speed of Garnett feed rolls 17, 18, 21 and 23 is identical, and a little faster than the speed of the fluted rolls 13 and 14. This is to enable the feed roll 17 to readily pick up the material as it is released from the fluted rolls l3 and 14. In one embodiment of the machine, the fluted rolls l3 and 14 and the upper rolls 18, 21 and 23 are all 4 inch diameter rolls and the lower roll 17 is 8 inch diameter. The purpose of clearing roll 23, which is mounted at a constant distance from the second upper roll 21, is to clear the second upper roll 21 of any material which may wrap itself around the roll. The material leaving between the lower roll 17 and the second upper roll 21 is picked up by the cylinder 25.

The cylinder 25 is supported by a main shaft 26 journalled in a bearing assembly 27 supported on the mounting structure 11. Regularly disposed about or connected to shaft 26 is the cylindrical structure generally referred to as the cylinder 25. This structure comprisesa pair of spaced end plates 28 adjacent the bearings 27. These end plates 28 are preferably formed of half inch steel plate and are provided with enlarged openings 29 to allow air to enter the cylinder 25 and subsequently be blown out by the fan-like action of the cylinder. As may be seen in FIG. 3 between the end plates 28 are spaced one or more intermediate plates 30. The latter are similar in construction to end plates 28 and also have enlarged openings of the type shown at 29 in FIG. 1. The intermediate plates are suitably keyed or otherwise attached to shaft 26. The perimeter 31 is also the perimeter of the cylinder 25 Rim bands 32 which may be in the order of 3 inches wide and one-half inch thick, are preferably welded to the peripheries of the end plates 28, and also to the peripheries of the intermediate plates 30 so that the cylinder 25 may be said to take the form of an open drum or spider. Extending transversely between the end plates 28 and secured by means of the aforesaid rim bands 32 are staves33. On a cylinder 25 of some 30 inches in diameter such staves are preferably in the order of from about 9% to 1 inch apart.

The cylinder rotates in the direction of the arrow in the accompanying FIG. 1 at a speed which has been found preferably to be between 550 and 1,500 r.p.m. The optimum r.p.m. varies considerably according to the material being processed. In any event, a 30 inch diameter cylinde'r rotating at 750 r.p.m. provides a rim speed in the vicinity of some 6,000 feet/minute. It has been found that a peripheral speed of approximately 4,00012,000 feet/minute is preferable, although speeds outside this range are operable. The cylinder 25 is driven conventionally at a speed which may be varied according to the material being processed but however is kept relatively constant while a specific material is passing through the machine. In the embodiment shown in FIG. 4, a 40 HP motor 51 drives the 30 inch diameter cylinder 25 by means of a V-belt drive 52. The pulley sizes may be changed in order to vary the speed of the cylinder.

Upon the staves 33 are two or more rows but preferably three or four rows of primary needles 34. These are illustrated in FIG. 3. The needles are inclined towards the direction of rotation or the direction of travel preferably at an angle of some 45. These needles are preferably some 1% inches long and spaced about 16 to 1 inch apart. Upon the leading edge of each stave 33 is a comb 35, having thereon a set of outwardly projecting teeth 36 and such teeth may desirably be some or 12 to the inch and about one-fourth inch deep from tip to trough.

As a preferred embodiment, the projecting teeth 36 on the comb 35 are saw tooth in shape and slant in one direction. The combs are then mounted so that the teeth on the first comb slant in one direction and the comb 35 mounted on the next stave 33 has teeth slanting in the opposite direction and so on around the periphery of the cylinder 25. It has been found that the combs may desirably be formed from No. 10 band backsaw blade stock in which the teeth are sharp, slanting in one direction, and function well to comb, shred fabric and aid in stretching, crimping and breaking filaments.

It may be found desirable to mount an additional comb 35 on the trailing edge of each or some of the staves 33 or even to mount the comb 35 on the trailing edge rather than the leading edge of the staves 33.

Surrounding the cylinder 25, and spaced from the tips of the needles 34, there is a casing 37 of general volute configuration and having enclosing side portions 38. The casing terminates at a longitudinal edge 39 to permit a draft of air to be drawn into the casing 37 above clearing roll 23, and between the end plates 28. Air intake openings 40 are also provided in the sides 38 of casing 37 around the bearing assembly 27. By virtue of the downward pressure of air entering through the intake mouth below the casing edge 39, material which is passing over the rotating cylinder 25 is sucked down towards the base of the needles 34. It may also be stated that the feed roll assembly 12 may preferably be capable of adjustment to left or right with respect to the accompanying FIG. 1, that is to say, closer to the cylinder 25 or further away from it toward the feed conveyor 10 according to circumstances and the nature of the product being processed. With the staves 33 set apart from about 16 to 1 inch and the provision of the air intake opening below the casing edge 39 it will be apparent that the staves 33, needles 34 and combs 35 rotating at a high speed induce a large flow of air within the casing and an air current of considerable velocity carries off the end product (B) through the volute discharge exit 41 of the casing 37.

In operation, the material (A) is spread out evenly on the feed apron 10. When the material leaves the feed apron 10 it is picked up by the two

fluted rolls

13 and 14. These rolls are to meter the material, and they also aid in guiding, holding and pressing the material. Leaving the fluted rolls l3 and 14, the material is picked up by the lower Garnett wire covered feed roll 17 and passed between the lower roll 17 and the two upper Garnett wire covered feed rolls l8 and 21. To prevent pulling or jerking through the feed rolls and to present the material in an even and regular flow, this special feed roll assembly I2 is required. The feed roll assembly 12 provides two functions, the first is to continuously forward the material at a low speed to the cylinder 25 and the second is to restrain the material while it is being withdrawn by the cylinder 25. It has been found that once the material commences feeding through the feed assembly 12 and is picked up by the cylinder 25 the power driving the feed rolls is required to prevent the feed rolls rotating too fast.

After leaving the feed roll assembly 12 the material is withdrawn by the slanted sharp pointed needles 34 in the staves 33. The material is slowly released by the feed roll assembly 12 at the rate of 6-12 feet/minute. Opening needles 34, catch the material, pierce it, and proceed to randomly separate, straighten and pull the filaments forward over the face of the cylinder 25. Through this pulling motion, filaments on the cylinder are randomly stretched. When the material is in the form of knitted or woven waste, the needles pick at this waste, and separate it into individual filaments, which are straightened and stretched.

When the material comprises a mass of undrawn continuous filaments of a cold-drawable synthetic polymer, this stretching action draws'the filaments. The stretching action, however, is a random one, consequently some filaments stretch until they break, and others are only partially drawn before being broken, thus forming undrawn segments randomly spaced along the length of the filaments. Heat is developed during the drawing of the filaments and this is dispersed by the fan-like action of the rotating cylinder which forces a large volume of air through the filaments on the cylinder.

As the cylinder continues to rotate, the filaments are pulled down to the base of the pointed needles 34, aided by the suction from the fan-like action of the rotating cylinder. The filaments then come in contact with the secondary teeth 36 on the combs 35. The teeth 36 perform a combing action on the filaments while being stretched around the cylinder.

When the material comprises a mass of undrawn continuous filaments, it appears that these secondary teeth aid in placing a crimp in the continuous filaments as the stretching steps pull short sections of the filaments across the secondary teeth 36 which act as knife edges. The resulting discontinuous filaments have crimps in random directions spaced randomly along their length. These teeth also appear to roughen the surface of the filaments so they have rough surface segments similar to wool.

The cylinder rotates, and the continuous filaments eventually break. Thebreaking action appears to vary from one filament to the next. Some filaments are stretched to their limit and break with a snapping action which at this high speed causes the ends of the filaments to recoil and form crimps such as hooks or curls. Other filaments may be broken by a severing action from the secondary teeth 36. Some filaments appear to have ragged ends as though they have been broken by crushing. The broken filaments are then propelled away from the machine by the flow of air induced by the cylinder 25 in the casing 37 and blown into a batch room or condenser where the air is separated from the filaments.

In the case of the initial material being a mass of undrawn continuous filaments of a cold-drawable synthetic polymer, strong filaments, such as nylon, can easily be drawn approximately half way round the cylinder before they break. It has been shown that discontinuous filaments produced by this method vary in length up to approximately 28 inches.

It has been found that the relationship between the cylinder speed and the feed speed is important. If the feed speed is a certain ratio of the cylinder speed, then this ratio should preferably be maintained regardless of any change in either cylinder speed or feed speed. If the initial material is undrawn continuous filaments of a cold-drawable synthetic polymer and the peripheral speed of the cylinder 25 is reduced much below 4,000 feet/minute, then the filaments tend to wrap themselves around the cylinder and are not broken or blown out with the broken filaments. The average length of filament produced may be varied by changing the ratio between the feed speed and the cylinder speed.

In the case of continuous filaments, it has been found that one pass through the conversion machine may not always be sufficient to produce a satisfactory product. Therefore, it is sometimes necessary to have two or more passes through the machine to avoid problems in further processing the material. For a two pass system, two machines may be set up in tandem, the first machine blowing the broken filaments into a condenser which releases the air, and allows the filaments to drop onto the apron of the second machine.

Some of the discontinuous filaments produced by this machine from continuous filaments of a cold-drawable synthetic polymer are excessively long, and need further processing to take advantage of their full potential as a useful product. The majority of machines for the processing of staple fiber into spun yarns can only take staple fiber of limited length. The discontinuous filaments of this invention may be further processed through a conventional type garnetting machine or carding machine. The discontinuous filaments are taken off the final garnet or card roll, put into a sliver or roving, and coiled in a large can or put on a balling machine and wound into a large ball. The discontinuous filaments in the sliver or roving form are then fed into a gilling machine or pin drafter to align the filaments. When the filaments are aligned one to the other they may be passed through a precision staple cutting machine and cut to the desired maximum lengths.

Some of the synthetic undrawn continuous filaments are very tender and brittle, and to convert them to a good usable product a fair amount of heat must be applied directly to the continuous filaments while being drawn. This heat may be applied by a hot fluid such as steam or hot air directly onto the mass of continuous filaments, or by means of a heated element such as an electrically heated element in one or more of the feed rolls or by other well known heating devices while the mass of continuous filaments is being forwarded at a low speed and withdrawn at a high speed.

Polyethylene terephthalate continuous filaments in an undrawn condition are tender and quite brittle. When a moist heat such as steam is applied directly to the filaments, they can be drawn readily and in the drawing the filaments gain considerable strength. To process undrawn polyethylene terephthalate continuous filaments live steam may be applied through pipes directly to the material. As may be seen in FIG. 5, a steam pipe 53 is placed between the feed rolls l3, l7 and 18 and a second steam pipe 54 is placed between the feed roll 21, and the main cylinder 25. In this embodiment, the clearing roll 23 is removed, and the steam pipe takes the place of the clearing roll 23. Steam from the pipe 54 blows on the feed roll 21 and acts as a cleaner to remove any fibrous matter sticking to feed roll 21. The

steam pipes

53 and 54 run from one end of the feed rolls to the other. The pipes have a series of small holes in rows about three-eightsinch apart. Steam is blown onto the material as it emerges from the fluted feed rolls l3 and 14, proceeds over the lower roll 17, between the first upper roll 18 and the lower roll 17, between the second upper roll 21 and the lower roll 17 and as the material is being picked up by the needles 34 of the cylinder 25. Because the filaments of polyethylene terephthalate are found to be tender to this process the speed of rotation of the cylinder 25 is preferably reduced to between 600 to 750 rpm. With the addition of steam jets or other types of heating, undrawn continuous filament polyethylene terephthalate can be converted from weak, tender, brittle undrawn continuous filaments to discontinuous filaments of good strength and cohesive qualities.

The mass of discontinuous filaments of this invention are produced from a mass of undrawn continuous filaments of a cold-drawable synthetic polymer and have a number of unique features. These features all appear to have one thing in common and that is randomness. Filament lengths may vary up to a maximum of approximately 28 inches, and the average length by weight of the filaments is in the order of 2.5 to 5.0 inches with a standard deviation of at least 1.2 inches. The lengths of the filaments are randomly distributed, although as seen from the average weight, there are fewer long filaments.

The filaments have a wool like quality in that they have crimps or bends, randomly spaced along the length of the filaments. These crimps appear to be in random directions and are sometimes referred to as: curls, twists, convolutions, loops, hooks and folds among other terms. In many instances, the filaments appear to have a crimp at either one or both ends in the form of a hook or a curl. A hooked end is defined as one having a sudden direction change of at least within 1 cm. of the filament end, and a curled end is defined as one having a slow direction change of at least 360 within 1 cm. of the filament end. A sketch of two typical filaments is shown in FIG. 6, illustrating a hooked end 55 and a curled end 56. The randomness of the bends in the filaments contribute towards the woollike quality with respect to hand and bulk of the product.

The filaments are drawn, but have undrawn segments occurring throughout the length of the filaments. These undrawn segments of increased denier, sometimes referred to as blips, nubs or slubs, are of random size and are randomly spaced along the length of the filaments. The undrawn segments are shown at 57 in FIG. 6. Thus the denier range can vary considerably along the length of one filament. The average transverse dimension of the cross section of the filaments, in the case of filaments having round cross sections this is the average diameter, varies in the range of 2.5 to 8.0 cms. X 10*. The standard deviation of the average transverse dimension, along the filament length and from filament to filament is at least 0.08 cms. X 10*. This standard deviation is higher than any presently known synthetic staple fiber.

Tests which have been carried out by determining the birefringence of nylon 66 filaments, show a high average draw ratio, within the range of 2.0 to 3.5 with a standard deviation of at least 0.6.

The unique features of this product contribute to discon-' tinuous filaments having bulk and resilience closely resembling wool. The product processed through the conversion machine may be further processed by garnetting, gilling and cutting to shorter lengths as required. When spun into yarn or formed into batts the discontinuous filaments exhibit cohesive properties that closely resemble first grade wool.'Woven or knitted fabrics from yarns made from discontinuous filaments of this invention arefluffy and resilient. Furthermore, unlike many synthetic fiber fabrics, the filaments due to their excellent cohesive properties do not form shiners or bundles of married filaments in a finished fabric.

The product of this invention has been found suitable for blankets, carpets and knitted goods such as sweaters and socks, and is suitable for non-woven fabrics. Furthermore, no doubt due to the random features of the discontinuous filaments, finished articles made therefrom have been found to dye evenly. Due to their excellent cohesiveness, the filaments lend themselves to blending with natural fibers, such as wool or with other less cohesive synthetic staple fibers.

MODE OF OPERATION OF INVENTION Example 1 Undrawn nylon 66 continuous filament tangled waste, which when drawn would give 3 denier per filament, was prepared by the addition of a lubricant comprising a fiber lubricating oil emulsified with water. The conversion machine had a cylinder of 30 inches in diameter. Twenty staves were equally spaced around the circumference of the cylinder, and each stave had 340 to 350 needles, 1%. inches long. A comb having 12 teeth per inch was mounted on the trailing edge of each stave making a total of 20 combs.

The prepared material was fed through the feed roll assembly at a surface speed of 6% feet per minute and picked up by the needles of the cylinder rotating at 880 r.p.m., equivalent to a-surface speed of 6,900 feet per minute. Two passes were made through the conversion machine, followed by two passes through a conventional garnetting machine. The resulting product was in the form of a sliver.

Example 2 Six denier per filament partially drawn nylon 66 continuous filament in tangled form was prepared by lubricating with a regular fiber lubricating oil. The conversion machine used in the test had a cylinder of 30 inches in diameter. Thirty staves were equally spaced around the circumference of the cylinder, and each stave had 140 needles. A comb having 10 teeth per inch was mounted on the leading edge of each stave making a total of 30 combs.

The prepared material was fed through the feed roll assembly at a surface speed of 6% feet per minute and picked up by the needles of the cylinder rotating at 958 rpm, equivalent to a surface speed of 7,400 feet per minute. The material was passed twice through the conversion machine followed by one pass through a conventional garnetting machine. The resulting product was in the form of a sliver.

Example 3 Undrawn nylon 66 continuous filament tangled waste,

which when drawn would give 12 denier per filament was converted to a sliver form under the same conditions as Example 2.

Example 4 Undrawn nylon 66 continuous filament tangled waste, which when drawn would give 18 denier per filament, was

prepared by the addition of a lubricant as in Example 1. The conversion machine used in the test had a cylinder of 30 inches in diameter. Twenty staves were equally spaced around the circumference of the cylinder, and each stave had 340 to 350 needles, 1% inches long. A comb having 12 teeth per inch was mounted on the trailing edge of each stave, making a total of 20 12 teeth per inch combs, and a comb having 10 teeth per inch was mounted on the leading edge of every other stave, making a total of l0 1 0 teeth per inch combs.

The prepared material was fed through thefeed roll as sembly at a surface speed of 6% feet per minute and picked up by the needles of the cylinder rotating at 1,000 rpm, equivalent to a surface speed of 7,900 feet per minute. The material was passed once through the conversion machine followed by one pass through a conventional garnetting machine. The resulting product was in the form of a sliver.

Example 5 Undrawn DACRON polyester continuous filament in tangled form, which when drawn would give 12 denier per filament, was prepared by lubricating with a regular fiber lubricating oil. The conversion machine used in the test had a cylinder of 30 inches in diameter. Twenty staves were equally spaced round the circumference of the cylinder, and each stave had 340 to 350 needles. A comb having 12 teeth per inch was mounted on'the trailing edge of every other stave making a total of 10 combs.

Low pressure steam was used in the manner shown in FIG. 5

to preheat the material before entering-the feed roll assemblyto assist the drawing process of the conversion machine. The surface speed of the material through the feed roll assembly was 6% feet per minute. The material was then picked up by the needles of the main cylinder rotating at 880 rpm, equivalent to a surface speed of 6,900 feet per minute. The material was passed twice through the conversion machine, followed by one pass through a conventional garnetting machine. The resulting product was in the form of a sliver.

The cross section of the filaments from this example and from Examples 6 and 7 were examined before and after conversion. It was found that the cross sections of the undrawn and partially drawn filaments before processing were round in shape, but after conversion the cross sections were irregular in shape, varying from round to almost square, and more closely resembled the cross section of wool filaments.

Example 6 Twelve denier per filament partially drawn DACRON polyester continuous filament tangled waste, was prepared by lubricating with a regular fiber lubricating oil. The conversion machine had the same arrangement as that used in Example 5.

Low pressure steam was used to preheat the material before entering the feed roll assembly to assist the drawing process of the conversion machine. The surface speed of the material through the feed roll assembly was 6% feet per minute. The material was then picked up by the needles of the main cylinder rotating at 675 rpm, equivalent to a surface speed of 5,300 feet per minute. The material was passed once through the conversion machine, followed by one pass through a conventional garnetting machine. The resulting product was in the form of a sliver.

Example 7 4.5 denier per filament partially drawn DACRON polyester continuous filament tangled waste was converted to a sliver form under the same conditions as Example 6.

Example 8 Partially drawn polypropylene fiber waste which had been cut ofi" a yarn package into short lengths, was prepared by lubricating with a regular fiber lubricating oil. The conversion machine had the same arrangement as that used in Example 1.

The prepared material was fed through the feed roll assembly at a surface speed of 6% feet per minute and picked up by the needles of the cylinder rotating at 1,000 rpm, equivalent to a surface speed of 7,900 feet per minute. The material was passed once through the conversion machine followed by one pass through a conventional garnetting machine. The resulting product was in the form of a sliver.

Example 9 Partially drawn 4 denier per filament nylon 6 continuous filament in tangled form was converted to sliver form under the same conditions as Example 8 except the material was passed twice through the conversion machine.

The products made in the example were compared against the following known products:

Regular grade nylon 66 staple 1 A 3 denier per filament crimp set nylon 66 staple fiber processed on a Pacific Converter machine.

Regular grade nylon 66 staple 2 A 6 denier per filament nylon 66 staple fiber cut to 4 inch lengths.

Regular grade nylon 66 staple 3 An 18 denier per filament crimp set nylon 66 staple fiber cut to 3 inch lengths.

Regular grade nylon 66 staple 4 A 15 denier per filament nylon 66 crimped staple fiber cut to 4 inch lengths.

Regular grade acrylic staple 1 A 4% denier per filament ORLON acrylic staple fiber processed on a turbo stapler.

Regular grade acrylic staple 2 A 5 denier per filament Japanese acrylic staple fiber cut to 4% inch variable length on a Pacific Converter machine.

Regular grade polyester staple A 1% denier per filament DACRON polyester staple fiber cut to 1% inch lengths.

Waste producer nylon 66 staple l to 6- These samples represent products made form drawn nylon 66 on a conventional rag picker or garnetting machine. None of these waste products exhibited all the properties of the product of the present invention, and when formed into a sliver they did not have the cohesiveness of the present fibers.

Wool l-Australian virgin wool, combed and shrink proofed.

Wool Z-New Zealand wool, straight from the sheep.

MEASUREMENT OF LENGTH PROFILES BY WEIGHT Each sample to be analyzed was laid out on a velvet board so that the short filaments were at one end, and the long filaments at the other. All the filaments up to 1 inch were removed and weighed, followed by the samples from 1 to 2 inches and then 2 to 3 inches, etc. until there were no filaments remaining. The total weight of the sample was determined and the normalized weight of each length category was determined by dividing through by the total weight. The data obtained was key punched, and analyzed by a data reduction program to provide the average length by weight and the standard deviation of length by weight for each sample.

In plotting the length/weight profile for each sample it was found that the profile tended to be bimodal, (i.e., have two peaks). Furthermore, it was found as may be seen by referring to Table 1 that in comparison with other synthetic staple products, the length profiles were very broad. The standard deviation of length/weight of the samples of this invention was at least 1.2 and the samples of synthetic staple products show a standard deviation of less than this figure with the exception of No. 1 sample of waste producer nylon 66 staple. In reviewing the length/weight profile of this sample, it is observed that the majority of the fibers are of one length, with a tail of extra long fibers. The dispersion of fiber lengths is not a random dispersion.

TABLE 1 Standard deviation Av. length of length Sample by wt. (ins) by wt. (ins) Example 1 nylon 66 3.74 1.82 2 nylon 66 4.35 1.61 3 nylon 66 5.00 2.27 4 nylon 66 3.50 1.81 5 polyester 3.14 3.14 6 polyester 4.40 2.02 7 polyester 2.90 1.20 8 polypropylene 3.66 1.49 9 nylon 6 4.18 1.66 Regular grade nylon 66 staple 1 3.65 0.36

2 3.50 0 3 2.50 0 4 3.50 0 Regular grade acrylic staple l 4.15 1.07 2 4.53 0.64 Waste producer nylon 66 staple 1 1.60 1.21 2 1.57 0.77 3 1.38 0.65 4 1.61 0.67 5 1.60 0.88 6 2.00 0.93 Wool 1 3.18 1.04 Wool 2 3.89 0.63

MEASUREMENT OF BULK DENSITY AND MODULUS The samples were first all pin drafted into a sliver form to insure a common basis for comparison. Filaments of each different sample were selected, weighed and placed in a 1,000 cc. graduated cylinder. A 1,000 gram weight exactly fitting into the cylinder was placed into the cylinder, and the volume of the compacted filaments recorded. An additional 1,000 gram weight was lowered into the cylinder, and the new volume occupied by the filaments was recorded.

The bulk density for each load was calculated as follows:

. Sample weight in gms Sample volume in on cm The bulk modulus was calculated as follows:

' 2000 gm X volume at 1000 gm load (Vol at 1000 gm-Vol at 2000 gm) X-sect. area of cylinder As may be seen from the accompanying Table 2 the samples of the present invention show the bulk density of the product Density in gms/cu cm Bulk Modulus in gms/sq em of the present invention is in the same order as wool, and the bulk modulus of the product is in the range or lower than that of wool. This low bulk modulus contributes to the wool like feel of the fiber, and the fiber tends to feel softer and more luxurious than the other synthetic staple products.

TABLE 2 Bulk Bulk Density Density at at Bulk 1000 gms 2000 gms Modulus gms/cu gms/cu (gms/ Sample cm) cm) sq cm) Example 1 nylon 66 0.128 0.153 231.8 2 nylon 66 0.116 0.145 196.8 3 nylon 66 0.094 0.126 148.1 4 nylon 66 0.084 0.111 160.5 5 polyester 0.107 0.141 153.6 6 polyester 0.117 0.139 226.1 7 polyester 0.118 0.139 238.5 8 polypropylene 0.076 0.101 152.9 9 nylon 6 0.113 0.144 170.8 Regular grade nylon 66 staple 1 0.068 0.093 141.2 2 0.078 0.112 123.1 3 0.062 0.081 166.5 4 0.080 0.109 143.4 Regular grade acrylic staple 1 0.072 0.091 181.8 2 0.091 0.109 235.3 Regular grade polyester staple 0.059 0.095 99.8 Waste producer nylon 66 staple 1 0.141 0.177 180.9 2 0.104 0.124 225.8 3 0.101 0.137 271.8 4 0.106 0.132 276.4 5 0.109 0.139 247.9 6 0.109 0.136 276.0 Wool 1 0.090 0.118 225.8 2 0.082 0.102 188.4

FILAMENT TRANSVERSE DIMENSION PROFILE tension to keep the filament taut. The clamped filament was placed in the path of the laser beam. The projected diffraction pattern from the laser indicated the transverse dimension of the filament on a calibrated chart. Five measurements per filament were taken, the measurements being approximately equally spaced along the threadline.

All the data from each sample was first run through the analysis for descriptive statistics. The data was then analyzed by an analysis of variance technique for standard deviation to describe the variation along the length and filament to filament variation.

The samples of the present invention were compared with wool, regular grade synthetic staple fiber products, and staple fiber made from waste products. The present samples showed a very high along the length transverse dimension variation and a generally high filament to filament variation as can be seen in the following Table 3 where: X is an unbiased estimate of the standard deviation of the transverse dimension along thread lines computed by the components of variance technique and Y is an unbiased estimate of the standard deviation of the filament to filament average transverse dimensions computed by the components of variance technique.

The present samples have a standard deviation of the transverse dimension of at least 0.08 cm. X 10' for both along the filament length and filament to filament dimensions. The other synthetic samples do not meet this requirement, either the X or the Y figure or both are below the 0.08 cm. X 10" dimension.

TABLE 3 Average transverse X Y dimension Sample cm 10' crnXl"cm 10" Example 1 Nylon 66 3.14 0.27 0.30 2 Nylon 66 3.24 0.18 0.09 3 Nylon 66 5.53 0.78 1.18 4 Nylon 66 4.06 0.40 0.20 5 Polyester 3.90 1.40 2.40 6 Polyester 5.66 1.57 2.46 7 Polyester 2.66 0.09 0.45 8 Polypropylene 8.09 0.18 0.22 9 Nylon 6 3.72 0.71 0.85 Regular grade nylon 66 staple l 2.02 0.005 0.03 2 2.88 0.006 0.01 3 6.05 0.028 0.51 4 4.75 0.016 0.15 Regular grade Acrylic staple 1 2.86 0.37 0.025 2 2.49 0.007 0.06 Waste producer nylon 66 staple l 3.34 0.034 1.17 g 2 2.44 0.054 0.43 Wool l 2.62 0.13 0.32 Wool 2 4.32 0.32 0.42

FILAMENT SHAPE ANALYSIS The number of hooked and curled ends, the crimp and the roughness were measured according to the following procedure. One hundred filaments were examined for each sample. Each filament was selected at random from the sample and the number of curled ends and hooked ends recorded. A curled end is defined as one having a slow direction change of at least 360 within 1 cm of the filament end and a hooked end is defined as one having a sudden direction change of at least 180 within 1 cm of the filament end.

FIG. 6 shows a filament having a typical hooked end 55 and a filament having a typical curled end 56.

The filament was pulled straight and the distance from end to end measured. The filament was then released, allowed to contract and the distance from end to end measured. The percentage of the reduction in length, known as percentage crimp, was then determined.

. The roughness of the filament was then compared with that of Australian virgin W001 (W001 l). The filament was held at one end and gently stroked between finger and thumb. The approximate percent of the length of the filament which had a wool like roughness was recorded.

, As can be seen from the attached Table 4 the samples of the present invention exhibit a high percentage of hooked ends as compared with the regular grade staples. More particularly, approximately 20-50 percent of the filaments have hooks or curls on at least one of the filament ends.

TABLE 4 hooked curled roughness Sample ends ends crimp Example 1 Nylon 66 46 2.0 4.4 0.7 2 nylon 66 39 .0 5.8 7.4 3 nylon 66 35 0.5 7.1 27.8 4 nylon 66 36 1.0 5.6 2.3 5 polyester 32 0 6.7 72.5 6 polyester 33 2.0 6.9 73.3 7 polyester 32.5 1.5 4.3 2.7 8 polypropylene 23.0 4.0 10.4 16.0 9 nylon 6 38.5 1.0 5.9 0.6

Regular grade nylon 66 staple l 2.5 0 9.7 44.2 2 11 0 9.1 73.8 3 7.0 0 17.4 99.9 4 10.5 0.5 11.5 99.4 Regular grade acrylic staple 1 11.5 0 3.7 21.4 2 10.5 0 5.8 50.3 Regular grade polyester staple 4.0 0 20.0 0 Waste producer nylon 66 staple 1 26 2.0 5.3 0

2 15 0.5 6.2 4.7 3 37 5.0 5.4 O 4 13.5 1.5 5.8 1.1 5 21 0.5 8.6 55.3 6 23 1.5 3.9 0 W001 1 13 0.5 7.9 Wool 2 30 2.5 8.2 87

OPTICAL BIREFRINGENCE Birefringence is a measure of the optical path length difference of light polarized, parallel to and perpendicular to the filament axis (referred to as retardation) and normalized by the filament diameter.

Retardation Birefrin ence g F lament diameter The measurement has been correlated with the physical draw ratio of nylon 66 by H. DeVries reported in Journal of Polymer Science XXXIV pages 761 778 (1959) and was found to be:

l Birefringence Draw Ratio Example 10 The sliver prepared according to Example 1 was passed through a conventional gilling machine to align the filaments.

The gilled sliver was cut into 4 inch lengths to form a staple fiber. The resulting staple fiber was then processed by the conventional woolen system of processing, where the fibers were first carded into a roving and then spun into a yarn on spinning frame. The yarn was knitted into sweaters and socks.

The knitted products exhibited excellent hand and bulk. The products were fluffy and resilient, and no shiners or bundles or married fibers were apparent in the knitted fabrics. The knitted products dyed evenly and no streaks or uneven patches were apparent.

Example 1 1 Waste nylon 66 drawn tire cord in the form of a plied yarn was prepared by the addition of a lubricant comprising a fiber lubricating oil emulsified with water. The conversion machine had a cylinder 30 inches in diameter. Twenty staves were equally spaced around the circumference of the cylinder, and each stave had 340 to 350 needles. A comb having 12 teeth per inch was mounted on the trailing edge of each stave making a total of -12 teeth per inch combs and a comb having 10 teeth per inch was mounted on the leading edge of every other stave making a total of 10-10 teeth per inch combs.

The prepared material was fed through the feed roll assembly at a surface speed of 6% feet per minute and picked up by the needles of the cylinder rotating at 880 r.p.m., equivalent to a surface speed of 6,900 feet per minute. The material was passed once through the conversion machine, followed by one pass through a conventional garnetting machine. The resulting product was in the form of a sliver.

The resulting product was in broken filament form having varying length and random crimps along the length. When gilled and cut to staple lengths, the product compared favorably with other waste producer nylon 66 staple fibers.

Example 1 2 ORLON acrylic drawn continuous filament fiber in regular form was prepared by the addition of a lubricant as in Example l l. The conversion machine used in the test had a cylinder of 30 inches in diameter. Thirty staves were equally spaced around the circumference of the cylinder, and each stave had 140 needles. A comb having 10 teeth per inch was mounted on the leading edge of each stave making a total of 30 combs.

The prepared material was fed through the feed roll assembly at a surface speed of 6% feet per minute and picked up by the needles of the cylinder rotating at 950 r.p.m., equivalent to a surface speed of 7,400 feet per minute. The

material was passed once through the conversion machine, followed by one pass through a conventional garnetting machine. The resulting product was in the form of a sliver.

The resulting product was similar to that produced in Example 1.

I claim:

1. A mass of discontinuous filaments of a cold-drawable synthetic polymer having randomly distributed variable lengths, the filaments being cold-drawn but having undrawn segments randomly spaced along the lengths, and crimps in the filaments in random direction spaced randomly along the lengths.

2. A mass of discontinuous filaments of a cold-drawable synthetic polymer having randomly distributed variable lengths, an average length by weight within the range of from 2.5 to about 5 inches with a standard deviation of at least 1.2 inches, the filaments being cold-drawn but having undrawn segments randomly spaced along the filament lengths, and crimps in the filaments in random directions spaced randomly along the lengths.

3. The mass of discontinuous filaments of claim 2 wherein the lengths of the filaments vary up to a maximum of approximately 28 inches.

4. The mass of discontinuous filaments of claim 2 wherein the average transverse dimension of the filament cross-section is in the range of from 2.5 to 8.0 cms. X10 with a standard deviation along the filament lengths and filament to filament ofat least 0.08 cm. X 10'.

5. The mass of discontinuous filaments of claim 2 wherein approximately 20 to 50 percent of the filaments have hooks or curls on at least one of the filament ends.

6. A mass of discontinuous filaments of polyhexamethylene adipamide having randomly distributed variable lengths, an average length by weight within the range of from 2.5 to 5 inches with a standard deviation of at least 1.2 inches, the filaments being cold-drawn but having undrawn segments randomly spaced along the filament lengths, an average transverse dimension of the filament cross-section in the range of from 2.6 to 8.0 cms. X 10* with a standard deviation along the filament lengths and filament to filament of at least 0.08 cm. X 10"", crimps in the filaments in random directions spaced randomly along the lengths, and an average draw ratio within the range of 2.0 to 3.5 with a standard deviation of at least 0.6.

7. A mass of discontinuous filaments of polyethylene terephthalate having randomly distributed variable lengths, an average length by weight within the range of from 2.5 to 5 inches with a standard deviation of at least 1.2 inches, the filaments being cold-drawn but having undrawn segments randomly spaced along the filament lengths, an average transverse dimension of the filament cross-section in the range of from 2.5 to 8.0 cms. X 10' with a standard deviation along the filament lengths and filament to filament of at least 0.08 cm. X 10"", crimps in the filaments in random directions spaced randomly along the lengths, and irregular filament cross-sections closely resembling wool filament cross-sections.

8. The mass of discontinuous filaments of claim 4 in the form of a sliver.

9. The mass of discontinuous filaments of claim 4 in the form of a staple fiber, wherein the discontinuous filaments have been cut to staple lengths.

10. The mass of discontinuous filaments of claim 4 in the form of a spun yarn.

11. A blend of staple fibers comprising staple fiber lengths of the mass of discontinuous filaments of claim 4 together with natural or synthetic staple fiber.

Claims

4. The mass of discontinuous filaments of claim 2 wherein the average transverse dimension of the filament cross-section is in the range of from 2.5 to 8.0 cms. X 10 3 with a standard deviation along the filament lengths and filament to filament of at least 0.08 cm. X 10 3.

6. A mass of discontinuous filaments of polyhexamethylene adipamide having randomly distributed variable lengths, an average length by weight within the range of from 2.5 to 5 inches with a standard deviation of at least 1.2 inches, the filaments being cold-drawn but having undrawn segments randomly spaced along the filament lengths, an average transverse dimension of the filament cross-section in the range of from 2.6 to 8.0 cms. X 10 3 with a standard deviation along the filament lengths and filament to filament of at least 0.08 cm. X 10 3, crimps in the filaments in random directions spaced randomly along the lengths, and an average draw ratio within the range of 2.0 to 3.5 with a standard deviation of at least 0.6.

7. A mass of discontinuous filaments of polyethylene terephthalate having randomly distributed variable lengths, an average length by weight within the range of from 2.5 to 5 inches with a standard deviation of at least 1.2 inches, the filaments being cold-drawn but having undrawn segments randomly spaced along the filament lengths, an average transverse dimension of the filament cross-section in the range of from 2.5 to 8.0 cms. X 10 3 with a standard deviation along the filament lengths and filament to filament of at least 0.08 cm. X 10 3, crimps in the filaments in random directions spaced randomly along the lengths, and irregular filament cross-sections closely resembling wool filament cross-sections.

8. The mass of discontinuous filaments of claim 4 in the form of a sliver.

10. The mass of discontinuous filaments of claim 4 in the form of a spun yarn.