US3462815A - Strand treatment - Google Patents

Description

5 sheets-sheet 1 FiledNov. 20, 1967 INVENTOR. 05597 /f ITAA/7 f7 c C# [f1/Tiffy Aug. 26, 1969 R. K. STANLEY y 3,462,815

' 'STRAND-TREATMENT Filed Nov. 2.0, 1967 l -5 sheets-sheet. f3

U8 26V, 1969 *R1 K. STANLEY 3,462,815

STR/mn TREATMENT Filed Nov. 20, 1967 v E Sheets-Sheet Z INVENTOR. O, l( .STA/WH United States Patent O 3,462,815 STRAND TREATMENT Robert K. Stanley, Media, Pa., assignor to Techniservice Corporation, Kennett Square, Pa., a corporation of Pennsylvania Continuation-impart of application Ser. No. 302,758,

July 31, 1963. This application Nov. 20, 1967, Ser.

No. 684,230 The portion of the term of the patent subsequent to Apr. 9, 1985, has been disclaimed Int. Cl. E02g 1/08 U.S. Cl. 28-72.14 13 Claims ABSTRACT F THE DISCLOSURE This application is a continuation-in-part of my copending patent application, Ser. No. 302,758 led July 31, 1963, now U.S. Patent 3,376,622, granted Apr. 9, 1968, which was a continuation-in-part of my prior application, Ser. No. 216,524 Aug. 13, 1962 and since abandoned.

Textile strands can be produced by extension of fiberforming compositions through spinneret orifices and collection of the resulting filaments or fibers. Many polymeric fiber-forming compositions so treated produce strands of relatively low tensile strength because of relatively low macromolecular orientation with respect to the longitudinal axis. In most such compositions the orientation and tensile strength can be increased readily because the strand components (usually continuous filaments) are drawable to an attenuated and extended condition of high orientation from which there is little or no tendency to return to the original condition. Nylon strands, for example, can be drawn so readily at or near room temperature that they are commonly indicated as being colddrawable. The strand temperature normally increases during drawing because of intermolecular friction and sliding friction with any snubbing pin or similar means employed to localize the drawing action. In actual practice the strand, regardles of composition, may be heated to facilitate and to localize the drawing operation.

Strands of continuous laments, whether oriented or unoriented, are inappropriate for many uses because of their rectilinearity, which is conducive to slickness, translucency, and low bulk, all of which can be eliminated or modified by any of a variety of processes usually called crimping or texturing Nearly all of those processes (e.g., edge-crimping, gear-crimping, jet-crimping, and twist-crimping) tend to extend the strand axially while deforming it transversely of the longitudinal axis and, therefore, may be expected to be compatible with an immediate pre-drawing operation. Studer-crimping, however, which alters the configurationof (and incidentally heats) strands by longitudinal compression thereof, may be expected to be separated from the drawing process in location or time (except for such drawing being prior, usually long prior) rather than adapted to follow immediately upon an attenuation of the strand to increased length. Attempts to crimp thermoplastic textile strands fice within a short time following drawing thereof have required that the strands be heated or wet during both steps or both heated and wet during one or both steps. There is a considerable need for improved apparatus, technique, and results.

A primary object of the present invention is provision of a novel drawing and crimping process for textile strands.

Another object is crimping of textile strands by compression along the strand axis immediately following permanent extension therealong.

A further object is elimination of the customary requirement tht thermoplastic strands be heated or wet (or both) during drawing and crimping.

Other objects of this invention, together with means and methods for accomplishing the various objects, will be aparent from the following description and the accompanying diagrams.

FIG. 1 is a schematic representation of drawing and crimping steps with intervening time period;

FIG. 2 is a schematic representation of a continuous draw-crimping process without intervening time period;

FIG. 3 is a perspective view (somewhat stylized) of a drawing system useful according to this invention;

FIG. 4 is a front elevation of a stutfer-crimper for use according to this invention;

FIG. 5 is a side elevation of the stuffer-crimper of FIG. 4;

FIG. 6 is a sectional plan of the same stuffer-crimper taken at VI-VI of FIG. 5;

FIG. 7 is a front elevation of a modification of apparatus according to this invention;

FIG. 8 is a front elevation of a further modification of apparatus according to this invention;

FIG. 9 is a side elevation of a length increment of monofilament textile strand in unoriented or only partly oriented condition;

FIG. 10 is a side elevation of the same increment of the strand of FIG. 9 after attenuation to increased length to orient it;

FIG. l1 is a side elevation of the oriented length increment of the strand of FIG. 10 buckling under axially compressive stress;

FIG. 12 is a side elevation of the same strand length increment crimped into a generally U-shaped configuration;

FIG. 13 is a side elevation (on reduced scale and somewhat stylized) of successive length increments crimped as in FIG. 12; and

FIG. 14 is a side elevation (on a much further reduced scale and also somewhat stylized )of a considerably greater length of crimped strand than shown in FIG. 13.

In general, the objects of the present invention are attained by attenuating an essentially dry polymeric textile strand to increased length and immediately thereafter compressing the strand axially to buckle successive length increments thereof, into a characteristic stutter-crimped configuration, without necessity for the stand to be heated externally for drawing but optionally providing for such heating. The invention cornprehends particularly such process as an improvement in stutter-crimping. Certain apparatus for drawing and immediately stutter-crimping textile strands comes within the purview of this invention, as indicated below.

FIG. 1 shows schematically Zone 11 wherein a strand is attenuated to increased length or drawn and zone 13 wherein the strand is crimped, as by any conventional system. Intervening Zone 12, shown in broken lines and traversed by an arrow leading from zone 11 to zone 13, represents the period (excessive) of time intervening between drawing and crimping. FIG. 2 shows schematically drawing zone 15, wherein the strand is treated as in zone 11, and compressive crimping zene 16 contiguous thereto according to this invention. The arrow indicates the passage of the strand immediately to the crimping zone from the drawing zone without `appreciable time intervening. The meaning of this will be apparent from the following details of the apparatus and process of this invention.

FIG. 3 shows, in perspective (stylized by omission of supporting, heating, driving, or other elements), rolls 21, 22, and 23 at the input end of a drawing zone, useful according to this invention, and rolls 31, 32, and 33 at the output end of the zone. Located in the space between the two sets of rolls is draw pin 27, use of which is optional. Strand 20, whose direction of travel is indicated by arrows, proceeds generally from left to right, passing about a quadrant of roll 21, downward through the nip of rolls 21 and 22, about the lower half of roll 22, upward through the nip of rolls 22 and 23, and over a quadrant of roll 23. It then makes a single turn about draw pin 27, after with it is denoted as 20. After leaving the draw pin the strand proceeds about a quadrant of roll 31, downward through the nip between rolls 31 and 32, about the lower half of roll 32, and then upward through the nip between rolls 32 and 33.

It will be understood that at least one of the rolls in each of these two sets is driven by suitable motive means (not shown) and that all the rolls within each set rotate at constant speed, whether driven directly by the motive means or indirectly by contact (essentially non-slipping) with one another. The surface speed of the rolls in the second or forwarding set (31, 32, 33) is greater than the speed of the rolls in the first or input set. The draw pin does not rotate but is fixed so as to snub the strand passing about it. The pin may, but need not, be heated by any conventional means( e.g., electrically or by steam, preferably supplied internally) as is customary in the art of strand drawing.

With some strand compositions it may be helpful to heat one or both sets of rolls (in addition to, or instead of, the draw pin). Heating the first set of rolls preheats the strand for drawing, possibly rendering it easier to draw, incidentally also preheating it for crimping-as may the drawing step itself. Heating the Second set of rolls at least sufficiently to prevent the drawn strand from cooling in the interim (however brief) is conducive to a steady and high degree of crimping. Although not illustrated, methods and means for heating the rolls, preferably internally, will come readily to the mind of a person skilled in the art; e.g., by circulation of heated fluid therein in known manner or electrically as disclosed in my U.S. Patent 3,111,740. The herein illustrated arrangement of three rolls in each set, with their axes in a cornrnon plane, two of the rolls flanking and being contiguous with the other roll is a preferred arrangement, but it is not imperative for the practice of this invention, as will be apparent hereinafter. There is not, according to this invention, any provision for heating the crimped or crimping strand in the stuffing chamber itself.

FIGS. 4, 5, and 6 show, in front and side elevation and sectional plan, respectively, stuffer-crimper 41 useful laccording to this invention. Rolls 31, 32, and 33 are shown incorporated in this apparatus, the latter two functioning also as stuing feed rolls. The supporting frame comprises base plate 42, front plate 43, back plate 44, and top plate 45, all secured together by suitable means (not shown).

` Upstanding facade 46 is secured similarly to the front plate. Tubular stuing chamber 50, which is nearly square in cross-section, is held in place against the front of the facade by four washers 51 overlapping the side edges of the front of the chamber :and supported on four wing screws 52 threaded into suitable apertures in the facade. The front wall of the chamber overlaps portions of rolls 32 and 33, and the rear wall does likewise, down to the roll nip, while the side walls terminate adjacent the rolls, thereby forming a close-fitting entrance to the chamber for strand stuffed thereinto by the rolls. The upper end of the chamber is covered by cap 55, which has ears 56 overlapping the front and back walls of the chamber and pivoted thereto by pintles 57. Extension spring 59 stretched from pins 58 on the cap to pins 60 on the chamber Walls bias the cap closed against the otherwise open top of the charnber.

Motor 61 affixed to the top surface of top plate 45 has shaft 63 extending to the rear through journal 62 upstanding from and secured by bolts 67 to the rear face of back plate 44. Aixed to the end of the motor shaft is pulley 64 interconnected by belt 65 to pulley 66 on the end of shaft 73, which carries roll 33 at its front end and extends through the front and back plates and also carries gear 69. Meshing with this gear is gear 68 on the end of shaft 72, the other end of which carries roll 32. Stub shaft 71 journaled in front plate 43 carries roll 31.

Located below rolls 32 and 33 are several components not being used as stuffer-crimper 41 is shown in FIGS. 4, 5, and 6. They are guide block 75, affixed to the facade by screw 76, and overlying guide clip 77, which is secured to the guide block by bolt 78 at the side. Both the guide block and clip extend arcuately toward the nip of the rolls. Use of these guide elements (and non-use of roll 31) appears in the embodiments shown in FIGS. 7 and 8, which are described hereinafter.

In the preferred embodiment already described, strand 20 is attenuated to become strand 20 in the drawing zone between tirst set of rolls 21, 22, 23 and faster running second set of rolls 31, 32, 33, the strand passing in essentially non-slipping contact with the rolls in each group. Immediately after having been drawn to increased length and thereby molecularly oriented, strand 20 is fed upward through the nip of rolls 32 and 33 and thus stuffed into the entrance of chamber 50. The chamber itself is filled with accumulation 20 of crimped strand, shown (stylized, for clarity) in FIG. 4 by cutting away of part of the front wall of the chamber, and is otherwise unheated and may be positively cooled (e.g., by circulation of a coolant-not shown-between the exterior and interior walls thereof) as disclosed in my U.S. atent 3,111,740, to cool the strand in crimped configuration, preferably as soon as it assumes such configuration.

Because the entrance to the stuffing chamber is always full during crimping operations each straight-length increment of strand entering the chamber is compressed axially (i.e., longitudinally and is forced to buckle, much as an overloaded structural column buckles. Continual buckling of successive length increments at the chamber entrance produces a crimping of the strand. Of course, the continued stuing of the strand into the chamber forces the terminal part of the strand laccumulation therein to emerge gradually therefrom between the spring-loaded cap and the upper end of thev chamber. Emergent crimped strand 20" is in relaxed condition and is wound up onto cone 79 driven by contact (through the layers of strand on it) with drive roll 80.

FIG. 9 shows, from the side, a short length of unoriented (or only partly oriented) monotilament strand 20. In transverse cross-section it is round, although that is not essential. FIG. l0 shows a like amount of strand 20', attenuated to increased length and thereby oriented. FIG. 1l shows the'same length increment of strand 20 at an early stage of buckling under axially compressive stress. FIG. 12 shows the same length increment,vnow designated 20, completely buckled into a generally U-shaped configuration such as exists inside the confining chamber. FIG. 13 shows, on a much smaller scale, a longer length of strand 20, including several buckled length increments, showing the generally curved arms of the U-shaped configurations (or crimps) stylized to the extent of being shown apart or separated although in the chamber there is little or no such separation. FIG. 14 shows, on an even smaller scale, relaxed crimped strand 20 such as is produced according to this invention.

Although the drawings illustrate only a monofilament strand, it will be understood that the term strandI as used herein includes also a multiiilament strand and that shorter lengths (e.g., staple) than usually termed continuous may be present. Suitable strand compositions will come readily to the mind of a person skilled in the textile arts. Prominent among the suitable compositions are the nylon (polycarbonamides), e.g., 66-nylon (i.e., polyhexamethylene adipamide), also 6-nylon, ll-nylon, 6l0-nylon, and fiber-forming copolymers thereof, including terpolymers. Other suitable polymeric materials for strands to be treated according to this invention include most of the linear polymeric fiber-forming materials, such as polyhydrocarbons (e.g., polyethylene, polypropylene), polyesters (e.g., polyethylene terephthalate), polyacrylonitrile and copolymers of acrylonitrile with other vinyl compounds, also copolymers of vinyl chloride and vinylidene chloride, and polyurethanes. This list is simply exemplary and is not intended to be exhaustive of suitable compositions, lmost or all of which are thermoplastic.

If a heated draw pin is used the appropriate temperature for it wil depend upon the characteristics of the strand composition and the speed of the strand over the draw pin. Appropriate processing speeds normally lie in the range of from one hundred to one thousand yards per minute (y.p.m.), but somewhat slower or faster speeds may lbe employed. For 66-nylon at an input of 100 y.p.m. and output of 400 y.p.m. (draw of 4X) the draw pin temperature may conveniently be between 150 and 250 C. The speed at which the strand is ted into the stuiiercrimper coincides with the output speed from the drawing zone, of course, and the roll temperature preferably prevents the strand from cooling before entering the crimper. The ratio of that speed to the speed at which the strand is fed into the drawing zone is essentially the draw ratio and .usually is at least two (draw of 2X and ratios of six or more are appropriate for some compositions. If desired, the drawing may be performed stepwise (eg, two successive draws of 2X to provide an overall draw of 4X), but one drawing step usually will sufiice and is preferable except perhaps in the instance of very high overall draw ratios.

As previously indicated, preheating of the strand is not required for crimping according to this invention and may not be required for drawing because of the immediacy of succession of those respective steps and of the heat engendered therein. Moisture content of the strand, if appreciable, may have a deleterious effect upon the desired treatment or its results. Therefore, the strand should not be wet, the preferable content of water and/ or any lubricant or softening, swelling, or plasticizing agent or solvent, all of which may be collectively referred to as moisture) being less than about by Weight. A strand at such low moisture content may be considered as essentially dry or moisture-free for the purpose of the present invention. The relative humidity in and about the chamber should not exceed about for best results with the usual textile strand compositions, the upper limit of humidity varying somewhat according to the moisture content and sensitivity of the composition.

While the illustrated three-roll arrangement is preferred at each end of the drawing zone, it is possible to use other roll arrangements, such as godets, if desired. The nip of rolls 32 and 33 may constitute a junction of the drawing and crimping zones, thereby effectively reducing to zero the length of the otherwise intervening path portion mentioned above. FIGS. 7 and 8 show (in front elevation, but rotated 90 clockwise) the crimper of FIGS. 4, 5, and `6 but with the strand passing therethrough being fed directly by and between rolls 32 and 33 in line with their common tangent (through the roll nip). Inasmuch as essentially non-slipping contact may be difficult toattain at a pressure that will not damage the strand, additional rolls ahead of rolls 32 and 33 may prove useful. When, as illustrated, the compressive crimping is accomplished by means of a stutter-crimper, the end of the drawing zone should not be further from the beginning of the crimping zone than about three diameters (measured along the strand path) of the stuffing rolls. Thus, in FIG. 7, added pair of nip rolls 82 and 83 are so located, and strand 20' passes therebetween. The rate of strand travel in such intervening portion of the strand path may be substantially the same `as at the end of the drawing zone; it should not be less and may be more. In both FIGS. 7 and 8 the strand passes between guide block 75 and overlying clip 77 to center it along the nip of rolls 32 and 33. When using all three rolls, as in FIGS. 4 to `6, it may be desirable to locate a pigtail or other guide ahead of the first roll and centered from end to end thereof for a like purpose.

Other variations in or modiiications of the described apparatus `and process may be made without involving a departure from the inventive concept. Any similarly useful compressive crimping device may replace the illustrated Studer-crimper, which is merely exemplary, as is the spring-loaded cap as the device for applying backpressure to the strand accumulation in that crimper. Such a crimper may have a stufling chamber with a round bore and a plunger therein as the back-pressure element, for example; also useful is a stutter-crimper having a frctionally retarded back-pressure device of wheel-like or gear-like configuration, as disclosed in U.S. Patent 3,027,619. Alternatively, lateral pressure alone may be relied upon as in my U.S. Patent 3,279,025. Except where windup control may be minimized or even dispensed with, as in the arrangement of last mentioned patent according to my further pending patent application, Ser. No. 567,245 tiled July 22, 1966, now U.S. Patent 3,386,142, granted June 14, 1968, windup of the crimped yarn expelled from the chamber preferably should be synchronized to accommodate the yarn so expelled without, however, withdrawing yarn from ahead of the back-pressure device. The portion of the cap covering the chamber as hereinabove may be used to control the windup rate, or a sensing device inside the chamber, such as is disclosed in my U.S. Patent 3,280,444, may be employed.

Strands crimped according to the present invention, are characterized by excellent crimp (i.e., are set) notwithstanding absence of conventional strain relieving features, which have been customary despite the complication and expense attendant thereon. Other beneiits and advantages of this invention, which produces crimped textile strands of exceptional bulk and crimp doubtless will become apparent and accrue to those who undertake to practice it.

The claimed invention:

1. In strand-crimping, the improvement comprising compressively crimping a drawn, essentially dry textile strand immediately upon completion of the drawing thereof to increased length.

2. Strand-crimping process according to claim 1, wherein the strand is drawn throughout a irst zone and is crimped throughout a second zone, the beginning of the second zone bordering on the end of the iirst zone.

3. Strand-crimping process according to claim 1, wherein the strand is unheated throughout the compressive crimping thereof.

4. Strand-crimping process according to claim 2, wherein the strand is heated preparatory to the compressive crimping step and is maintained free of temperature increase during the crimping step.

5 Strand-crimping process according to claim 4, wherein the strand is cooled as soon as it assumes crimped coniiguration.

6. Strand-crimping process according to claim 3, wherein the strand is unheated preparatory to the compressive crimping step.

7. Strand-crimping process according to claim 6, wherein the strand is unheated throughout the compressive crimping thereof.

8. Process for ycrimping a textile strand, comprising withdrawing the strand from a source thereof and feeding it into a drawing zone `at a rst rate, forwarding the strand out of the drawing zone at a second rate greater than the first rate and thereby drawing the strand to increased length, and immediately compressively crimping the drawn strand in a crimping zones, the end 0f the drawing zone being contiguous with the beginning of the cr-imping zone.

9. Strand-crimping process according to claim 8, wherein the strand is forwarded out of the drawing zone and simultaneously fed into the crimping zone by being nipped between a plurality of moving solid surfaces bording both zones.

10. Strand-crimping process according to claim 9, wherein at least one of the plurality of moving solid surfaces in a feed roll of a stuffer crimper.

11. Strand-crimping process according to claim 10, wherein the plurality of moving solid surfaces comprises a set of three rolls, the rst and third of which are contiguous with the second, and the strand passes rst between the nip of the rst and second, then partly about the second and lastly between the nip of the second and third, the second and third rolls feeding the strand into a temporarily confining stuifer-crimping zone.

12. Strand-crimping process according to claim 9, wherein the moving solid surfaces are located at the entrance of a temporarily confining zone into which the strand is fed upon passing through the nip thereof and is thereby compressively crimped.

13. Strand-crimping process according to claim 12, wherein the moving solid surfaces comprise a pair of nip rolls, and a stuffing chamber with its entrance juxtaposed to the roll nip comprises the confining zone, and wherein the crimped strand is removed therefrom at a third rate less than the second rate.

References Cited UNITED STATES PATENTS 2,419,320 4/ 1947 Lohrke 28-72 2,686,339 8/1954 Holt 28-72 2,917,806 12/1959 Spence et al. 19-66 3,111,740 11/1963 Stanley 28-1 3,167,846 2/1965 Iwnicke 28-1 3,177,556 4/ 1965 Van Blerk 28-1 LOUIS K. RIMRODT, Primary Examiner

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