|Publication number||US3167845 A|
|Publication date||Feb 2, 1965|
|Filing date||Jul 19, 1960|
|Priority date||Jul 19, 1960|
|Publication number||US 3167845 A, US 3167845A, US-A-3167845, US3167845 A, US3167845A|
|Inventors||Haakon Claussen Ole|
|Original Assignee||Du Pont|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (14), Referenced by (3), Classifications (7)|
|External Links: USPTO, USPTO Assignment, Espacenet|
Feb. 2, 1965 o. H. CLAUSSEN BULK mu PROCESS AND mums Filed July 19, 1960 INVENI' OR OLE HAAKON CLAUSSEN ATTORNEY United States Patent 3,167,845 BULK YARN PRQCESS AND APPARATUS Ole Haakon Claussen, Wilmington, Del, assignor to E. l. du Pont de Nernours and Company, Wilmington, Etch, a corporation of Delaware Filed July 19, 196i), Ser. No. 43,891 14 Claims. (Cl. 28-41) This invention relates to a process and apparatus for producing crimped fibrous structures, and more particularly to means for producing relaxed fibrous structures having two different types of crimp superimposed upon each other.
Many recent improvements have been made in the field of crimping and bulking continuous filamentary yarns, particularly using fluid jet technology for accomplishing the bulking of the filaments within the yarn. These improvements have for the most part been limited to crimping single feed yarns and, therefore, have been rather costly from a production point of view. Also, most of the fluid crimping methods and apparatus have resulted in crimped yarns which have a residual shrinkage, which usually has to be removed by subsequent treating steps.
It is an object of this invention to provide a novel process and apparatus for producing relaxed crimped fibrous structures. A further object is to provide an economical process and apparatus for crimping synthetic fibrous structures at a high rate of production. Another object is to provide a simple procedure for obtaining fibrous structures having a combination of two different types of crimp superimposed upon each other. Other objects will appear hereinafter.
In accordance with this invention, synthetic organic thermoplastic fibers in the form of a strand, such as yarn or tow flattened into a sheet, or other continuous fibrous structure, are crimped in a relaxed condition on a surface by feeding the strand to a moving surface and conveying the strand on the surface, crimping the fibers on the surface by means of a stream of pl asticizing fluid directed against the fibers, separating the strand from the fluid, and setting the crimp in the strand. Dependent upon the effect desired, this general procedure can be carried out in several ways which are not equivalent. A highly effective procedure which produces a unique composite crimp is to forward the strand at high speed in the stream of plasticizing fluid to the moving surface so that the strand is struck in a plastic condition against the surface. This deforms the fibers to produce a crimp configuration which is particularly desirable for many applications and will be described in more detail subsequently. When the fibers are crimped in a tensionless state without being struck against the surface, a readily distinguishable simple form of crimp is obtained which is less desirable in general, although this is an effective relaxed-crimping process.
The strand can be converted to a plastic condition by the plasticizing fluid, in which case a compressible fluid (gas or vapor) heated to at least about 300 F. is preferable. However, the plastic condition can also be produced by a fluid which has a solvent or swelling action on the fibrous material, e.g., a solution of a swelling agent in a volatile organic liquid. If the strand is already in a plastic condition before it is acted on by the fluid, it is only necessary for the fluid to have sufficient plasticizing action to maintain the strand in a plastic con dition until the fibers have been crimped. Thus the strand can be preheated by passage over a heated surface or be fed directly from a melt-spinning operation in a heat-plasticized condition. The plastic condition can be provided by residual solvent remaining after a solventspinning operation, e.g., green cellulose acetate.
"'ice After the fibers have been crimped they are separated from the plasticizing fluid to set the crimp. The fluid is dispersed by striking against the surface. Surface irregularities assist in dispersing the fluid away from the fibers and can also improve the deformation of fibers crimped thereon. Preferably a screen surface, or other foraminous surface, is used which is permeable to pass fluid therethrough while retaining the fibers thereon for removal. The surface can be in the form of a drum, endless belt or disk on which the strand is conveyed away from the fluid stream after treatment. The fibers are crimped in a relaxed condition by moving this surface at a slower speed than the speed at which the strand is conveyed thereto. A single drum rotating at a slower surface speed can be used, but the strand can be separated quickly from the treating fluid by passing it through the nip between two such surfaces. An especially effective crimping action is achieved by forwarding the strand in a stream of plasticizing fluid to strike just prior to the nip formed by two surfaces moving together at a speed slower than the speed at which the strand is conveyed thereto, e.g., by crimping adjacent to the nip between the revolving surfaces of two drums, arranged so that the strand is separated from the treating fluid at the nip immediately after crimping. Preferably at least one of these surfaces is foraminous so that the fluid passes through after forwarding the strand against the surface. Crimping in this manner makes possible a more desirable fiber deformation and a more rapid setting of the crimp in a relaxed condition by separation from crimping fluid. When the strand is plasticized by heat, the process conditions can be controlled so that the crimp is set by cooling as the strand passes through the nip. However, the strand can be conveyed on one of the surfaces to allow more time for cooling, or positive cooling can be provided, as by cooling the surface or directing a cooling fluid onto the strand as it emerges from the nip.
FIGURES 1, 2 and 3 of the drawings illustrate a specific embodiment of apparatus for practicing the process of this invention in which thermoplastic yarn is simultaneously conveyed forward at high speed and converted to a plastic condition by means of a flowing fluid and is struck against a surface to mechanically deform the yarn and disperse the fluid, the yarn being thereafter set in the mechanically deformed state by the reversion of the yarn to a non-plastic condition.
FIGURE 1 is a front elevation of an embodiment of the apparatus of this invention;
FIGURE 2 is a side view of the apparatus of FIG- URE 1;
FIGURE 3 is an enlarged perspective View of the jet shown in FIGURE 1;
FIGURE 4 illustrates schematically a typical configuration of the novel yarn produced in accordance with this invention.
Referring to FIGURE 1, continuous fibrous strand 1, which may be a yarn, yarn warp, tow, non-woven batt, or the like, passes between fluid orifices 2 and 2 and through nip 3 of rotating hollow rolls 4 and 4 to windup roll 5. Before entering nip 3, the yarn passes through turbulent fluid zone 6 formed by the simultaneous intersection with the strand of streams of plasticizing fluid issuing from fluid jets 2 and 2' directed towards the nip to intersect with the strand at about equal angles a short distance from the nip so that the strand is conveyed forward at high speed and struck against the surfaces of the hollow rolls at the nip. The fluid is preferably heated to convert the strand to a plastic condition, but when the strand is preplasticized it is maintained in a plastic condition by the fluid. The strand is crimped and the fluid is dispersed at the nip, the strand then quickly reverting to a non-plastic condition. As shown, the crimped product 8 emerging from the nip is suificiently deplasticized to be wound up or handled'in any conventional manner. In the specific embodiment of FIGURE 1, fluid orifices 2 and 2 are contained in a single jet device 7 which also serves as a yarn guide, but quite obviously the fluid jets may be used which are entirely independent of one another and any yarn guide suitable for directing the strand into the focal region of the jets is satisfactory so long as the yarn passing through the turbulent zone of plasticizing fluid is subjected to sufficient force to provide the desired crimping action. In general, the jets should pro vide at least /2 sonic fluidvelocity and should intersect the strand at a distance of less than about 3 inches from the nip or other surface against which the strand is impinged.
As shown in FIGURE 2, a side view corresponding to FIGURE 1, the apparatus is suitable for treating a plurality of yarns simultaneously. The strand 1 may also be a tow in the form of a warp sheet. Jet orifices in the form of slots provide high velocity fluid streams of a width at least as great as the width of the warp of yarn forming the strand 1. This view also shows screen surface 10 provided on nip-rolls 4 and 4'. The fluid is dispersed therethrough into the roll interior indicated as hollow portion 9. The jet device 7 of FIGURES '1 and 2 is more clearly shown in the enlarged perspective view of FlGURE 3. The jet orifices 2 and 2' are passageways of generally rectangular cross-section which taper to relatively narrow slits 13 and 13' to discharge flattened streams of fluid at high velocity. They are arranged on each side of strand passageway 12 with the axes making an angle a therewith in the range from about to 75 so that the fluid streams converge on the strand emerging from slot 14 of the guide passageway and forward the strand to strike against screen surface 10.
In the above embodiment the fluid streams act on the strand after leaving the jet device 7, where thestrand is unconfined and open to the atmosphere. This is particularly advantageous in the process of the present invention. The linear focal region shown for treatment of a warp would, of course, be modified when crimping a single yarn or monofilament. The jets can be arranged to provide a focal region which is essentially a point. More than two jets arranged symmetrically around the yarn or monofilament, or a circular type of orifice, can be used. However, a Wide variety of jet devices can also be used which provide for action of fluid on a strand within the device, provided that they can be operated to convey the strand forward against the screen or other surface at a sufficiently high velocity to produce crimping. Such devices are disclosed in U.S. Patents No. 2,783,609, No. 2,852,906 and No. 2,869,967, and in Belgium Patents No. 581,303 and No. 573,230.
According to the preferred process of this invention,
there is provided a multifilament strand containing continuous filaments, said strand having a sawtooth crimp and the individual filaments in the strand possessing an additional crimp characterized by a random, three-dimensional, non-helical, curvilinear configuration. In addi tion, each individual filament has an additional crimp characterized by alternate S and Z twist sections throughout its length; having a random number of turns between twist reversals; having a random continuously varying angle of twist along its length; having a random number of twist reversals per inch; and having at least one 3 turn and at least one 2 turn per inch which have a twist angle averaging at least 5 or a twist intensity (angle) equivalent to at least 20 turns per inch. FIGURE 4 is a schematic illustration of this crimp in which the sawtooth crimp designated by the lines a, b, c and d is superimposed upon a multifilament strand in which the individual fibers x, y and z contain non-helical, curvilinear crimp as further defined hereinbelow.
For purposes of clarifying the operation of the present invention, V is defined as the speed. of the feed strand, that is, the speed at which an uncrimped strand is advanced into turbulent zone 6, the focal point of the fluid jets; V is defined as the speed of the yarn as it leaves the turbulent zone; V is the speed of thecrimped yarn as it passes through the nip of rolls 4,4 and, if no slippage occurs between .the yarn and the rolls, V is also the linear surface speed of these rolls; and V is the speed of the yarn passing to the next operation, e.g., the speed at which it is wound on take-up roll 5.
If V is equal to or greaterthan V and both are less than V only a random, three-dimensional, non-helical, curvilinear type of crimp i s-imparted to the yarn. When operating in this way the yarn'is not mechanically deformed by striking the surface but the surface does contribute to the effectiveness of the crimping process. For example, when the direction of yarn feed and the rotation of the rolls 4, 4 is reversed, so that the yarn passes through the nip before being subjectedto the fluid stream and is then pulled away, little or no crimp is produced although the apparatus can be used in this manner to stretch or draw fibrous structures.
If V V V there is produced a fibrous structure having an essentially planar zigzag type of crimp superimposed upon' a random, three-dimensional, non-helical, curvilinear type of crimp.
In most instances the take-up, speed V will'be somewhat greater than the roll speed V by a convenient amount for smooth operation. Some planar zigzag crimp will be pulled out during the normal operation of the process. Thus, the real or effective overfeed for a particular yarn will depend upon the relative speeds of V and V.,, which can be adjusted to give the desired amount and type of crimp.
In general,,V V V V are preferred conditions for producingthe novel products of this invention. For preparation of crimped fibrous structures having high bulk, the processing. conditions are adjusted so that V V is between 3 and 10, and V /V is between 1.5 and 5 (preferably between 2 and 4). For thev preparation of crimped fibrous structures having low bulk, processing conditions should be adjusted so that V /V is between 1.1 and 1.5, and V /V is between 1.05 and. 1.4.
Using a constant overfeed, the ratio of the amounts of the two types of crimp that may be produced in a strand can be varied by adjusting the velocity of the impinging fluid and the angle the fluid makes with the said yarn. The degree of planar zigzag type of crimp, e.g., number of crimps/inch, may be increased by increasing the overfeed of the strand or decreased by decreasing overfeed.
The process of this invention can be used to crimp and bulk any natural or synthetic plasticizable filamentary material. Examples of such filamentary materials include polyamides, such as polysebacamide, polyhexamethylene adipamide, polyundecanoiamide, polycaproamide, and copolyamides; polyesters and copolyesters, such as the condensation products of ethylene glycol with terephthalic acid (polyethylene terephthalate) or 2,6- naphthalic acid (polyethylene 2,6-naphthalate), ethylene glycol with a /10 mixture of terephthalic/isophthalic acids, ethylene glycol with a 98/2 mixture of terephthalic/ 5-(sodium sulfo)-isophthalic' acids, poly(diphenylolpropane carbonate), 1,4-bis(hydroxymethyl) cyclohexane with terephthalic acid to include trans/cis mixtures, and poly(diphenylolpropane isophthalate); acrylonitrile polymers, such as polyacrylonitrile and copolymers of acrylonitrile with vinylidene chloride, vinyl chloride, methyl acrylate; or anyv of the comonomers listed in Jacobson U.S. Patent No. 2,436,926 or Millhiser U.S. Patent No. 2,837,501; vinyl chloride and vinylidene chloride polymers and copolymers; polyurethanes, polyester amides, polyethylenes and polypropylenes (both linear and branched), polycarbonates; fluorinated ethylene polymers and copolymers such as polytetrafluorethylene and polymonochlorotrifluoroethylene and cellulose derivatives, such as cellulose acetate and regenerated cellulose.
The process and apparatus described herein are useful for crimping and bulking many different forms of fibrous structures as well as changing the crystallinity of these structures. For example, monofilaments, multi-filament yarns, tow, a sheet of warp ends, woven and knitted fabrics, and webs, batts, papers, and other non-woven fibrous structures may be processed which have suficient coherence and strength to be treated without being pulled apart, and the term strand as used herein refers to all of these. The yarn may be of textile denier or of heavier denier for carpet, tire, or other industrial uses. In all cases, the fibrous structure to be treated herein must be sufiiciently strong so that it is continuously self-supporting under the conditions of operation (will not pull apart or be disintegrated).
The foraminous surface used to receive a strand conveyed forward by the stream of plasticizing fluid will preferably be in the form of two screen surfaced hollow rolls. Two contiguous foraminous belts moving in the same direction at the same speed and passing between the nip of a plurality of hollow rolls arranged in tandem may also be used in a similar manner. When two rolls are used, they will normally be driven at the same surface speed, although they may be of the same or different diameters. Instead of the opposing fluid streams originating outside the rolls, stationary jets may be mounted inside but near the periphery of two screen-covered rolls having hollow stationary center shafts. The foraminous surface may suitably be a metal screen preferably made of stainless steel, but also may be made of plastic, glass, ceramic, or other material, or may be a perforated sheet, a perforated belt, parallel wires, or the like.
The turbulent fiuid used to treat the fibrous structures may be air, steam, or any other gas or vapor, i.e., a compressible fluid, which is capable of plasticizing the filamentary fibrous structures. superheated steam is the preferred fluid in the present process since it is a cheap and convenient source of high pressure i1 id with plasticizing action on the filamentary material.
The temperature of the fluid medium must be regulated so that the filamentary material does not melt. However, when treating filaments made from fusible polymers, the most effective bulking and crimping is usually obtained when the temperature of the turbulent fluid is above the melting point of the fiber. In this instance, the speed of the moving fibrous structure should be great enough to prevent melting of the filaments sufficiently to cause loss of their fibrous nature. Normally, the foraminous surface is not independenly cooled but nevertheless acts as a cooling medium for the crimped fibrous structure. It may be desirable in some instances to independently cool the roll surface and/ or the crimped fibrous structure at the point where the fibrous structure is separated from the roll surface. The fluid streams directed towards the moving fibrous structure from opposite sides may issue from two or more separate points or planes, or annularly or elliptically, provided the angle a between each fluid stream and the moving fibrous structure is greater than 5 and less than 75 and the fluid is directed in a generally concurrent direction with the moving fibrous structure.
The present invention provides a crimped fibrous structure which is relaxed and contains practically no residual shrinkage. The process may be controlled to give either a single type of crimp, which is the random, three-dimensional, non-helical, curvilinear crimp (described by Breen and Lauterbach in copending U.S. Serial No. 842,524 filed September 25, 1959, and now abandoned), or a composite of two types of crimp superimposed upon each other; namely, a planar zigzag type of crimp superimposed on this random, three-dimensional, non-helical, curvilinear crimp. The present process and apparatus is cheaper than known crimping processes, allows a greater flexibility in producing almost any desired crimp level, and allows a faster production of crimped products than 6. the prior methods of crimping which employed fixed reservoirs wherein the yarn and fluid, if one were used, were mechanically confined. The present process may be operated at least faster than prior methods for obtaining crimped synthetic filamentary materials at comparable crimp levels. in addition, the instant invention may be used to treat multi-ends of yarn or fabrics, with no width limitation, to give uniform crimping along the full width of the fibrous structure being treated. Also, the present invention produces crimped products which have greater uniformity of crimp and other physical properties than those produced in closed system jets, and requires less critical control during operation than prior closed, mechanically confined areas of turbulence.
EXAMPLE 1 A strand consisting of six ends of of continuous filament polyhexamethylene adipamide yarn (102068 /2 Z twist) in the form of two sections of three ends each is fed through apparatus of the type illustrated in FIG- URE 1. Each filament has an essentially trilobal cross section. The apparatus contains two planar slit jets and the fluid is steam. Each jet has an external aperture opening in the shape of a slit approximately 4 inch long and inch wide. These slit openings in the jets are positioned at a distance of approximately 1 /2 inches from the nip of two screen-covered rolls, and these slits are positioned at an angle of 40 to a plane passing vertically through the nip of the rolls and parallel to the axes of the two rolls. The distance between the two slit openings is approximately A1, of an inch. The polyamide yarn is fed into the passage between the two slit openings by feeding it into a tube positioned vertically between the two jets, said tube being separated inside by a wire in the middle of the tube. The yarn is fed in two sections of three ends each on either side of the wire inside the tube. The yarn is fed into the tube a speed of yards per minute (V The fluid which is fed to the two jets is superheated steam at 450 F. at a pressure of 80 p.s.ig. Each of the two rolls is of aluminum having a diameter of 12 inches, and is positively driven by external means. Each roll is covered with a stainless steel 30- mesh wire screen, and is hollow beneath the surface screen, except for the drive shaft, to permit exit of steam through the screen. Both screen-covered rolls are driven at a speed of 20 yards per minute (V The take-up speed of the yarn at the exit end of the nip is approximately 60 yards per minute (V and this yarn is collected on a positively driven take-up roll.
The uncrimped feed yarn and the crimped product yarn resulting from treatment according to this invention (both before heat setting as well as after setting at 215 F. in saturated steam for 5 minutes) are subjected to several yarn characterization tests. The results of these tests, shown in Table I, indicate that the physical properties of the bulky crimped yarn, having a random, three-dimensional non-helical, curvilinear crimp are superior to those of prior art bulked and/ or crimped yarns. The crimped yarn product has a combination of two types of crimps, namely, an essentially planar zigzag crimp superimposed on a yarn in which the individual filament possesses a random, three-dimensional, non-helical, curvilinear crimp. Therefore, the number of crimps per inch reported for the yarn product in Table I is the sum of the planar and three-dimensional types of crimp. When the strand is crimped at considerably higher speeds, under otherwise comparable conditions, similar results are obtained.
EXAMPLE 2 A strand consisting of 16 ends of continuous filament poly(ethylene terephthalate) yarn (l50430 twist) in the form of two sections of eight ends each is processed with the apparatus of Example 1, using superheated steam at 400 F. and 80 p.s.i.g., the other conditions being the same as in Example 1. The results are shown in Table H.
TABLE I ,YarnCriinp Elongation (Percent) Initial Tenacity Elonga Modulus Toughness No. crimps Residual Denier (gmsl tien* (gm./ (gm.-cm. per inch Shrinkage As Exercised Boiled-off denier) (Percent) denier at denier) (Percent) Collected 100% elong.)
Uncriniped feed yarn". 13.0 5. 06 31.2 40. 7 1.1 Crimped yarn (before setting) 102 76 70 14. 7 4. 65 62. 3 13. S 2.1 13.0 Crimped yarn (heat set) 132 95 110 16. 8 4. 30 59. 7 13. 9 1. 8 16. 0 0
TABLE II Uncrimped feed yarn... 4.14 5. 23 24. 6 80. 3 1.0 Crimped yarn (before setting) 4. es 4. 37 35. 4.3. 7 1. 1 1s. 5 0 Crimped yarn (heat set 5. 62 3. 28 50. 8 33.8 1.2 17.5 0
*The yam crimp elongation in percent (extended length of yarn with all crimp removed) (original crnnped length) X100 Since many difle-rent embodiments of the invention may be made without departing from the spirit and scope thereof, it is to be understood that the invention is not limited by the specific illustrations except to the extent defined in the following claims.
1. The process for manufacture of a bulked fibrous strand which comprises feeding a strand of synthetic organic thermoplastic fibers to a turbulent stream of plasticizing fluid to crimp the fibers, forwarding the crimped strand in plasticized condition at high speed in the stream of plasticizing fluid to a foraminous surface, moving the surface in substantially the direction of strand travel at a slower speed than the speed at which the strand is conveyed thereto to support the plasticized strand in relaxed condition, additionally crimping the relaxed strand solely. by directing a stream of plasticizing fluid against the fibers to crimp the fibers on the surface, separating the strand from the fluid, and setting the crimp in the strand.
2. A process as defined in claim 1 in which the surface is foraminous to disperse fluid therethrough and retain the yarn on the surface.
3. A process as defined in claim 2 in which the surface forms a nip with another surface, the surfaces bei-ng moved together at aspeed slower than the speed at which the yarn is conveyed thereto and arranged to pass the yarn through the nip after treatment.
4. A process as defined in claim 1 in which the fluid is a heated compressible fluid.
5. A process as defined in claim 1 in which the fluid is at a temperature above about 300 F.
6. A process as defined in claim 1 in which the fluid contains a swelling agent for the yarn.
7. A process as defined in claim 1 in which the surface is formed by revolving surfaces of two drums arranged to provide a nip through which the yarn is passed and at least one drum has a foraminous surface for separation of fluid from the yarn.
8. A process as defined in claim 7 in which the strand is composed of a polyamide and the plasticizing fluid is steam.
9. A process as defined in claim 7 in which the strand is composed of a polyester having an aryl group in the repeating units and the fluid is steam.
10. A process for crimping a synthetic organic fibrous strand which comprises forwarding the strandin a plastic condition axially through a zone of turbulence formed by the intersection of two jets of a compressible strand-' plasticizing fluid each having at least /2 sonic velocity, the jets being positioned .on opposite sides of the strand with each forming an angle of about 5 to about 75 with the strand position upstream from said intersection, decreasing the forward speed of the strand within a distance of less than 3 inchesafter entering the zone of (original crimped length) turbulence by striking the strand against a foram inons surface moving at a slower speed to produce a relaxed crimp, conveying the strand away from the plasticizing fluid on-the surface, and then removing the strand from the surface.
11. A process as defined in. claim in which the strand is composed of thermoplastic material, the compressible fluid is heated above about 300 F. to plasticize the strand, and the strand is deplasticized by cooling before removal from the surface.
12. Apparatus comprising a pair of rotatable hollow nip-rolls having foraminous surfaces, fluid jet means for directing a turbulent'stream of compressible fluid into the nip of said rolls to pass through said surfaces, strand feeding means for supplying a fibrous strand to the turbulent stream to be forwarded into and through saidnip of the rolls,:and take-up means for removing the strand from the rolls after passage through the nip.
13. Apparatus comprising a pair of rotatable hollow nip-rolls having foraminous surfaces, fluid jet means for passing a turbulent stream of compressible fluid into the nip of said rolls and through. said surfaces, said jet means comprising fluid jets positioned to direct streams of fluid toward the nip of said rolls so that the axes of the jet streams intersect a common tangent to the rolls which is perpendicular to the nip, the intersection being at a distance of less than 3 inches from the nip and at an angle of about 5 to about 75 with said tangent, strand feeding means for supplying a fibrous strand between said fiuid jets to be forwarded into and through; said nip of the rolls, and take-up means for removing the strand from the rolls after passage through the nip.
14. Apparatus as defined in claim 13 in which each jet stream axis intersects said tangent at an angle of between and References Cited in the file of this patent UNITED STATES PATENTS 588,812 Bessonette' Aug. 24, 1897 2,313,630 Dockerty Mar. 9, 1943 2,435,891 Lodge Feb. 10, 1948 2,760,252 Shattuck. Aug-28, 1956 2,807,862 Griset Oct. 1, 1957 2,869,967 Breen Jan. 20, 1959 2,874,443 Griset Feb--24, 1959 2,914,835 Slayter Dec. 1, 1959 2,964,900 Hicks Dec. 20, 1960 3,005,251 Hallden et al.- Oct. 24, 1961 3,016,599 Perry Jan. 16, 1962 3,036,357 Cook et a1 May 29, 1962 FOREIGN PATENTS- 1,225,587 France Feb. 15, 1960 (Corresponding British, 861,108, Feb. 15, 1961)
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|Citing Patent||Filing date||Publication date||Applicant||Title|
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|US6492020||Jun 16, 2000||Dec 10, 2002||E. I. Du Pont De Nemours And Company||Staple fibers produced by a bulked continuous filament process and fiber clusters made from such fibers|
|U.S. Classification||28/256, 19/66.00R, 57/246, 66/202|