US3780149A

US3780149A - Conjugate spinning process

Info

Publication number: US3780149A
Application number: US00525680A
Authority: US
Inventors: H Keuchel; W Polestak
Original assignee: Celanese Corp
Current assignee: Celanese Corp
Priority date: 1966-02-07
Filing date: 1966-02-07
Publication date: 1973-12-18
Anticipated expiration: 1990-12-18

Abstract

CRIMPED FILAMENTS ARE PREPARED BY SUBJECTING TWO STREAMS OF THE SAME POLYMER TO DIFFERENT TEMPERATURE OR SHEAR FORCES AND EXTRUDING THE POLYMER AS SEPARATE STREAMS THROUGH THE SAME SPINNERETTE ORIFICES.

Description

Dec. 18,1973 HW.KEUCHEL ETAL 3,780,149

CONJUGATE SPINNING PROCESS 2 Sheets-Sheet 1 Filed Feb. 7. 1966 INVENTORS K CHEL P STAK ATTORNEYS Dec. 18, 1973 H. W..KEUCHEL ETAL 3,780,149

CONJUGATE SPINNING PROCESS Filed Feb. 7, 1966 2 Sheets-Sheet 2 SHEATH COMPONENT SHEATH COMPONENT 'IIIII'I'I) CORE COMPONENT HERBERT W.

WALTER d. P

CORE COMPONENT :INVENTOR KEUCHEL. O L ESTA K BY OJ. film/$15M WW ATTORNEY United States Patent 3,780,149 CONJUGATE SPINNING PROCESS Herbert W. Keuchel, Long Valley, and Walter J. Polestak, Summit, N.J., assignors to Celanese Corporation Filed Feb. 7, 1966, Ser. No. 525,680 Int. Cl. B29f 31/10 US. Cl. 264-168 3 Claims ABSTRACT OF THE DISCLOSURE Crimped filaments are prepared by subjecting two streams of the same polymer to different temperature or shear forces and extruding the polymer as separlate streams through the same spinnerette orifices.

This invention is concerned with the production of crimped filaments, and in particular with the production of crimped filaments produced from only one polymer or from a homogeneous polymer mixture.

Various methods have been proposed and used to produce synthetic cirmped fibers or filaments which are used for bulked yarns and Wool-like fabrics. One such prior method has comprised the spinning together of two different polymers in such a way that the two polymers are not appreciably blended together but are bonded together to form a single filament in the cross-section of which the diverse polymers form two or more distinct zones which extend along the entire length of the filament. The extrusion of the single filament may be such that the two polymers are localized and extend longitudinally along the filament in a side-by-side relationship, or the extrusion may be such that one polymer forms a core which is surrounded by a sheath of the second polymer. As the different polymers have substantially different physical properties, such as differing residual shrinkage, the filament tends to crimp upon application of a suitable after-treatment, such as stretching and drying.

However, this method has often produced filaments not completely satisfactory. When the filaments are spun into yarn, the resulting fabrics are often deficient in bulk and cannot be sufficiently fulled by finishing operations. Additionally, the fabrics are usually deficient with regard to resilience and stretchability, as well as with regard to recovery from deformation such as crushing or glazing. The fabrics also have been found to be difficult to uniformly dye, because the two polymers often have such varied chemical compositions. Further, this method requires preparation and handling of two different polymers, and thus requires apparatus which must separately melt and separately transfer the two polymers to the point where the polymers are brought together to form a single filament.

Other methods of producing crimped filaments have been developed which attempt to overcome the abovementioned difficulties and disadvantages. For instance, it has been proposed to spin a crimped filament by using two solutions containing differing concentrations of the same polymer. If different solvents are used for the two solutions, however, separate apparatus must be used to mix and transfer the two different solutions; and in the case of systems where the spent solvent is regenerated to be used again, additional apparatus is necessary to separate the two solvents. If only one solvent is used, only one solution must initially be prepared, but thereafter the 3,780,1419 Patented Dec. 18, 1973 solution must be divided with one portion receiving additional solvent. Thus, these methods also essentially require the preparation of two separate flows of polymers with differing characteristics.

Accordingly, a general object of the present invention is the provision of a two-component crimped filament which substantially eliminates the disadvantages of twocomponent crimped filaments heretofore available.

A more specific object is the provision of a method and apparatus which utilize only one polymer to produce a two-component crimped filament.

A further object of this invention is the provision of a method and apparatus for producing a two-component crimped filament which requires the preparation of only one polymer and which eliminates the necessity of subsequent additions of other components.

Another object of the present invention is the provision of a method and apparatus for producing a two-component crimped filament having superior crimp retention and bulk characteristics.

Yet another object is the provision of a crimped filament which may be easily and uniformly dyed and which is thus suitable for yarns and wool-like fibers.

The present invention visualizes a melt spinning apparatus and process for producing two-component laminated filaments from a single polymer by separating the polymer into a plurality of flow paths and subjecting each of the flow paths or streams of molten polymer to different thermal and shear environments to change its respective melt flow or shrinkage characteristics. The flow paths are then recombined and passed through a single jet to form an integral, laminated filament which has superior crimp potential characteristics. The filaments may be of any desired size, for instance, between about 5 and 200 denier or finer.

A better understanding of the present invention may be obtained by reading the following detailed specification in connection with the accompanying drawings, in which:

FIG. 1 is a cross-sectional view of one form of melt spinning pack assembly utilized in the present invention, comprising two concentric chambers separated from each other by a cylindrical wall;

FIG. 2 is a cross-sectional view taken generally along the sectional line IIII in FIG. 1;

FIG. 3 is a sectional perspective of a fragment of a filament produced in accordance with the present invention;

FIG. 4 is a cross-sectional view of a form of circular pack assembly comprising two semi-circular chambers separated from each other by a straight wall;

FIG. 5 is a cross-sectional view taken generally along the sectional line V-V in FIG. 4;

FIG. 6 is a cross-sectional view taken generally along the sectional line VI-VI in FIG. 4;

FIG. 7 is a cross-sectional view of a filament of this invention having a T-shape cross-section; and

FIG. 8 is a cross-sectional view of a similar filament having a rectangular cross-section.

Referring first to FIG. 1, the upper chamber of the melt spinning pack 1 of the instant invention has an opening 3 through which a molten polymer stream may enter the pack. The polymer cflow may be supplied by a conventional screw extruder or by other equivalent means which pumps a polymer stream of a constant volume displacement through opening 3. The polymer stream is then separated into two flow paths by the

concentric chambers

5 and 7. These chambers are defined by the spinning pack wall 9 and an inner circular wall 10, and are dimensioned to break up the polymer stream into two flow streams of predetermined relative volumes. The two flow streams may have substantially equal volumes, or the volumes may differ from each other. A shear resistance medium 11 partially fills the inner chamber 5, while a medium 12 having differing shear resistance characteristics is disposed within the outer chamber 7. A circular heating element 13 surrounds the outer chamber 7 to supply a predetermined level of heat to the two flow paths or polymer streams as they pass through the shear resistance media in the two chambers.

Disposed directly below the two concentric chambers is a circular distributor plate 15, which includes a plurality of flow channels 17 and 19. The upper face of the distributor plate 15 may be best seen in FIG. 2, which shows the flow channels arranged into two groups of circular patterns, separated by circular divider or inner wall 10. Of course, a greater or lesser number of circular patterns may be provided as desired. The circular inner Wall separates the two groups of fiow channels so that the inlets of the flow channels 17 open into only outer chamber 7, while the flow channels 19- have inlets which open up only into the inner chamber 5. Referring again to FIG. 1, each of the flow channels may be seen to slant inwardly through the distributor plate s that each of the -flow channel outlets opens up into a relatively large outlet 21. While outlet 21 may be of a number of different shapes, the illustrated dovetail shape has been found to be of particular utility in producing the crimped filaments of the present invention. The circular divider 410 may extend downwardly into the large outlet 21 so as to keep the two separate polymer streams substantially unmixed as they leave the large outlet. A spinneret jet plate 23 is disposed directly under the distributor plate 15 and includes jet capillaries 25 located directly under each large outlet 21. Both the plate 15 and jet plate 23 are securely held in position by the support member 26.

It will thus be understood that a molten polymer stream enters opening 3 and is separated into two flow paths, each flow path being directed through a different chamber. As described earlier herein, each chamber contains a different shear-resistance medium and thus, although substantially uniform heat is applied to the polymer flow paths, or streams by the heating element 13, the stream passing through the more resistant or firmer size medium will be held up for a longer period of time than the remaining stream. Because of the longer hold-up time, the one stream is subjected to the heat longer than the other stream. Filtration sand having different fineness, such as different mesh sizes of silica sand or the like, has been found to be particularly effective in regulating the holdup time of the polymer flow path. The shear-resistance medium is retained and kept from being carried through the flow channels by a retainer 27 made of a suitable material, such as felt metal of a predetermined porosity.

For instance, in a preferred embodiment as shown in FIG. 1, the flow path directed through chamber 7 is held up for a predetermined period of time by the shearresistance medium such as silica sand 12 and finally enters the flow channels 17 and the large outlet 21, while the fiow path being directed through chamber 5, which contains the finer sand 11, is held for a longer period of time before entering the flow channels 19' and then the large outlet 21. The two flow paths are then recombined at the jet capillaries 25 to form single filaments. As the two polymer flow paths are not randomly intermixed, each single filament will be composed of two polymer fractions having differing thermal histories and thus has a cross-section which may be generally like that shown 4 in FIG. 3, wherein a single filament may be seen to be comprised of a polymer fraction 28 and a different polymer fraction 29. The differing thermal histories cause the melt flow characteristics of the two flow paths or streams to be changed, and the resulting fractions exhibit different shrinkage potentials to cause the filament to coil or crimp. For instance, in the case of typical fiber-grade oxymetehylene or acetal polymers a sufiicient difference in flow characteristics to produce the desired effect can be obtained by maintaining one portion of the polymer feed at about C. for an average residence time of about 380 seconds while maintaining the other polymer feed portion at about the same temperature for about 540 seconds.

It should be apparent to one skilled in the art that with slight modifications of the illustrated spinning apparatus each filament could be extruded in a manner so as to have a core of one polymer fraction surrounded by a sheath of the other polymer fraction, instead of having the abutting laminar structures shown in FIGS. 3, 7 and 8.

Various other methods of subjecting each of the flow paths to a different thermal history are envisioned by the present invention. For instance, instead of using different media such as filtration sand of different fineness in the two chambers, the depth of the medium in one chamber may be made different from that in the other or the geometric configuration of the two channels may be changed such that the polymer flowing through one chamber must travel a longer or more tortuous path than the polymer flowing through the other channel. Alternatively, the dimensions of the flow channels 17 and 19 might be changed in relation to each other to provide a smaller diameter for some of the flow channels than for the remaining flow channels. Another variation of the present invention en visions heating the polymer stream in one chamber to a higher temperature than the stream in the other chamber, for instance, by maintaining a decreasing temperature gradient between outer wall 9 and the center of inner chamber 5. Still another variation involves the use of chemically different media in the two chambers, such as the use of sand or other inert solid in one chamber, and, in the other, a catalytically active solid such as an aluminum silicate molecular sieve or other cracking catalyst which suitably accelerates the desired limited degradation of the polymer. Any of the above mentioned variations of the present invention can be adapted to produce desired equivalent changes of the thermal history or chemical degradation of the two polymer streams.

The previously discussed changes in the polymer streams thermal histories occur mainly in that polymer flow path or stream which is subjected to the thermally more severe conditions. For instance, with respect to most common melt-spun polymers, such as polyamides (nylon), polyurethanes, fiber-forming olefin polymers such as polypropylene or poly-3-methylbutene, oxymethylene polymers or polyethylene terephthalate, the increased hold-up time in a chamber causes the polymers molecular weight to be varied. In general, thermal decomposition leads to a reduction in the melt viscosity of a polymeric system. Thermal decomposition, however, may also lead to branching and cross-linking. This naturally causes an increase in melt viscosity and eventually gelling. Either of these changes will produce different shrinkage potentials with respect to the substantially unchanged polymer stream. Minor differences in melt viscosities have thus been surprisingly found to produce structural changes in the polymer which are sufiicient to alter its shrinkage potential and thereby result in the desired crimp. Hard to melt portions contained in a polymer stream or flow path, such as crystallites or gels will melt more easily and in a more uniform manner after such a polymer stream has been subjected to controlled degradation in accordance with this invention. Consequently, such portion will exhibit different crystallization behavior upon solidification than a substantially unchanged portion of the same original polymer.

After extrusion of the laminated filaments as described above, further treatment has been found to produce crimped filaments of higher quality. For instance, the amount of draw-down and the rate of draw-down of the filaments from the jet capillaries will effect the filament orientation and therefore the quality of the crimp of the filament. After take-up of the filament, stretching by conventional means was also found to vary the quality of filament produced by the present invention. For example, some samples of the filaments packaged at constant length were initially unbulked, but were found to bulk upon stretching, whereas samples stretched during spinning between the rolls and the take up machine bulked after spinning.

Heat setting after the draw-down and take up of the filaments was found to produce increased crimp in most instances. Samples heat set prior to bulking produced less bulk than the original filaments, but heat setting after bulking produced an increase crimp in the filaments. Heat setting, as used herein, refers to the process of subjecting yarn, free to shrink, to an elevated temperature in the range of between about 60 and 150 C. Optimum temperature depends, of course, on the particular polymer used.

The following examples are illustrative of the present invention rather than limitative. The following symbols will be utilized to describe the quality of the crimp of the filaments produced by the instant invention.

KEY TO THE BULK RATING SYMBOLS Symbol: Definition How and when crimp was developed 1 No crimp after take-up, no improvement.

2 No crimp after take-up, crimp after or during stretching or specified after-treatment.

3 Crimp after take-up.

Character and intensity of crimp A Long waves. B Short waves. C Short waves, beginning to spiral. D Spirals. E Intense spirals.

Uniformity of crimp X Fil to fil variation. Y Longitudinal variation.

EXAMPLE I A fiber-grade polypropylene (Profax 6559) was used in this example. Its intrinsic viscosity was between 1.7 and 2.2, determined in Decalin (c.=0.1% solution) at 135 C. Its melt index (according to ASTM D1238-57T) was 3.7 at 230 C. and 0.072 at 190 C. This polymer was passed in a molten state at a temperature of about 250 0., through a melt spinning pack constructed as illustrated in FIGS. 1 and 2 hereof. Silica sand of 30/40 mesh size was placed in the outer chamber 7 to a depth of 16 mm., while silica sand of 60/ 80 mesh size was placed chamber 5 to a like depth of 16 mm. A circular sand retainer was constructed of felt metal of 40% porosity. The average residence time at extrusion temperature of the molten polymer passing through chamber 7 was about 380 seconds while the average residence time at extrusion temperature of the molten polymer passing through chamber 5 was about 510 seconds. Seventeen flow passages, each having a diameter of .04 inch, were disposed around a oneinch diameter circle. The non-heat stabilized polypropylene was fed through the opening of the melt spinning pack by a conventional vertical screw feeding a metering pump at a controlled constant pressure of about 1000 6 p.s.i. The extruded filaments were heat set at C. for approximately thirty minutes.

Table I below summarizes the effects of diiferent extrusion temperatures and of heat setting upon the crimp of the produced filaments. As will be seen from this table, the stretched samples bulked upon packaging, while the constant length samples had to be stretched to produce satisfactory crimping. Heat setting the streached bulked samples increased the bulk to a still higher spiral crimp.

TABLE I Efieet of extrusion and spinning conditions on bulking [Extrusion rate: 4.0 g./min.]

Crimp ratin Extrusion Heat set 120 C. temp., C. Packaged Roll, Take-up, on After Block Pack mJmin. m./min. take-up As spun bulking 250 250 400 Constant 2-A-Y len h. 400 800 Stretched. 13-13 E 255 255 400 Constant 1 length. 400 800 Stretched- 8-B-Y E 260 260 400 Constant 2-A length. 400 600 Stretched- 3-B B 270 270 400 Constant 2-B-Y length. 400 800 Stretched- 3B,3-D D,E 245 245 400 800 do 3-B E EXAMPLE II TABLE II Effect of extrusion conditions on bulking [Extrusion rate: 4.0 g./min.]

Bulk rating Extrusion temp.,C. Before After Roll, Take-up, Block Pack m./min. m./min. (Heat setting) 195 195 c400 2-A. 800 2-A 400 800 3-B E 190 200 21%.

400 3-B A 400 800 3-B E The bulk rating symbols, previously explained, show that an increased rate of take-up of the produced filaments favorably affects the quality of the crimp. For instance, a high rate of take-up of 800 m./min. was found to produce short crimped waves in the filament before heat setting, and an intense spiraled crimp after heat setting.

EXAMPLE III In this example fiber-grade polypropylene was treated under different conditions to show the effect of varying the mesh size of the shear resistance material in combination with varying the extrusion temperature. The results are summarized in Table III.

TAB LE III Effect of Extrusion and Spinning Conditioyns on Yarn-Bulk Formation of Polypropylene Pack composition (mesh, sand) Outer chamber Stretch on Extrusion take-up, temp, C. mJmin.

Inner chamber 400 Bulk rating at given take-up speed, mJmin.

From this data it appears that filaments having excellent crimping characteristics may be obtained from passing fiber-grade polypropylene through a melt spinning pack of the present invention having seventeen flow passages of .04 inch diameters arranged as a one-inch circle. Placing 30/40 mesh silica sand in a depth of 16 mm. in the outer chamber and 40/50 mesh sand in a depth of 16 mm. in the inner chamber was found to give excellent results. An extrusion temperature of 265- 275 C. and a take-up speed of 400-800 m./minute may be seen from the table to give particularly desirable results. Additionally, Table III shows an apparent trend toward more intense crimping upon decreasing sand particle size and thus increasing the hold-up time of each polymer flow path.

EXAMPLE IV The acetal copolymer of Example II Was passed through a melt spinning pack of the instant invention under different conditions to show the effect of extrusion temperature, take-up speed and stretch on the bulk and texture development of filaments spun by the present invention. The results are summarized in Table IV.

Highly crimped filaments were obtained at take-up speeds greater than 400 m./minute over a temperature range from to 190 C. Filaments having intense spirals were produced after take-up at a high speed from an extrusion of approximately C. At a lower rate of take-up speed, intense spirals occurred at an extrusion 5 temperature of 175 C. Different combinations of conditions can thus be used to obtain similar fiber properties as desired.

TABLE IV Eficct oi extrusion and spinning conditions on yarn-bulk formation 0! polyacetal yam spun in a dual-chamber spinning pack Pack composition (mesh, sand) Bulk rating at given take-up speed,

m./min.

9 EXAMPLE v In this example the parent stream of the acetal copolymer of Example II was subjected to a differential chemical treatment. This was accomplished by passing one branch of the divided melt stream through a pack chamber containing silica sand while forcing the other stream through a diiferent chamber containing silica sand and a cracking catalyst. The catalyst used was an alumi num silicate molecular sieve compound (Linde Molecular Sieve Type 3X Lot 136980; as described in US. Pats. 2,882,243 and 2,882,244). In this example, the polymer portion going through the catalyst bed experiences a higher degradation than the other flow stream. Differential degradation for optimum spinning performance can be controlled by proper choice of purely thermal conditions (as in Examples I-IV), or by proper choice of both thermal conditions and chemical environment (Example V).

To illustrate the differential effect more quantitatively, the divided melt spinning pack shown in FIG. 4 was used in this example. Unlike the device illustrated in FIGS. 1 and 2, the pack shown in FIG. 4 permits separate recovery, and hence separate evaluation, of each of the differently treated polymer streams or filament. More particularly, referring to FIG. 4, the polymer enters the pack at 41, is then divided by a linear wall 42 such that both

chambers

43 and 44 assume the cross-sectional configuration of a half-circle (FIG. 5). The melt stream passing through chamber 43 is forced through a layer of silica sand 46; the other stream passing through chamber 44 encounters first the catalyst 45 and then a layer of silica sand 46. Both streams are kept separated (FIG. 6) in order to determine differences in molecular weight and fiber tensile properties as affected by their diiferential treatment. Each of the two jet holes 55 and 56 (FIGS. 4 and 6) were 0.02 inch in diameter and 0.1 inch in length. The data are presented in Tables V and VI.

In summarizing the data in Tables V and VI, the following conclusion can be stipulated:

Chamber Melt stream according to Fig. 4 43 44 Catalyst No Yes. Relative polymer degradation (based on inherent Low High.

viscosity).

Relative viscosity (based on polymer throughput High... Low.

rate per hole or denier per hole). Filament tensile properties:

(a) Tenacity Higher.. Lower. (b) Elnmmtinn (in D0, Spin-Line stability (based on maximum take-up do Do.

speed, Table VI).

EXAMPLE VI Self-bulking polyester fibers have been produced according to the spinning and extrusion procedures as Well as apparatus described in Examples I and III.

The process data are summarized below.

Polymer:

Fortrel" Fiber-grade polyethylene terephthaiate Inherent viscosity (determined in a solution of 0.1% polymer in a mixed solvent of- 7 phenol Spinneret: 17 holes 0.04 in. diameter 0.20 in. long each (holes located on a 1-inch diameter circle.

TABLE V Differential chemical degradation of one parent melt stream Pack content Chamber 43 Chamber 44 3.3 3.3. /80 60/80. Catalyst typ I Linde molecular sieve type 3X. Volume, -2.

Tensile properties Extrusion Elongation Tenacity,

Take-up Yarn, I.V. Denier percent g./d. TE Rate, Temp., s eed, g/min. C. m min. a b a b a b a b a b 1 Inherent viscosity LnNr; determined with a 0.1% solution oi polymer dissolvedi C solvent consisting of 98% p-chlorophenol and 2% a-Pinene.

1 See the following:

(a) Correpouds to properties obtained from spinningcapillary (56) going through Chamber 44.

(b) Corresponds to properties obtained from spinning capillary (56) going through 0 hamber 43.

TABLE VI Effect of ditierential chemical treatments on spinning speed Maximum take-up speed, Extrusion conditions m./min.

Tempera- Throughput rate, gJmin. ture, C. a B b 1 14 Same significance as in Table V.

After-treatments such as heat relaxation (a) over a heated plate, (b) in a vacuum oven, or (c) steam autoclave, caused shrinkage and increased crimp intensity of a rating of 2-C. Hot or cold drawing produced crimp ratings of about 2B.

EXAMPLE VII Rectangular and Tshape jets were employed to provide an asymetric geometry and possibly produce a preferred bending axis during bulking. The sheath and core polymer streams were combined, with minimum intermixing in the jet countersink. The special distribution of the two diiferent polymer fractions, comprising the final fiber, is predetermined by jet design and the location of the holes in relation to the two polymer streams. In this example, the rectangular or slot-shape spinneret produced a laminated filament having a rectangular cross-section as illustrated in FIG. 8. The spinneret containing capillaries with T-shape cross-sections was employed producing fibers of like cross-sections, whereby each leg of the T-configuration consists, primarily, of one or the other melt stream as illustrated in FIG. 7.

Extrusion and take-up conditions are similar to the ones shown in Example VI. The spun fibers were drawn over a hot shoe in order to improve fiber tensile properties, and subsequently boiled ofi, allowing the fibers to relax freely to develop crimp due to their diiferential shrinkage potential. Fibers with up to 18% crimp have been produced. Table VII summarizes these results.

TAB LE VII comprising dividing said single molten stream into at least two portions subjecting at least one of said portions to chemically different media to alter the melt viscosity of the polymer stream by reacting with said chemical media and jointly extruding said polymer portions to form unitary filament containing said polymer portions.

3. A process for producing crimpable filaments comprising the steps of producing a flow of a molten polymer, separating said flow into two flow paths, passing said flow paths through different heating zones substantially at melt spinning temperature, one of said zones containing a particulate solid which promotes degradation of the polymer, one of said flow paths being retained by one of said zones for a longer period of time than the other flow path is retained in the other zone, and recombining said flow paths to form a single filament comprised of two distinct polymer laminar, each laminar exhibiting a dilferent shrinkage potential.

Tensile properties and process conditions oi self-crimping polyester fibers Tensile properties Take-up Steam Quench Denier Ten., g./d. Elong., percent Spinneret Crimp, s eed, condicollar Quench cross-section percent m. min. tion No. 1 medium As is Boil-ofi As is Boil-ofl As is Boil-oi?J Rectangular....... 18 100 4 Preeooiedair.. 16 1 1 19 16 100 4 d 16 20 2 1.4 30 12 7 100 4 s 17 3 2 60 9 11 300 4 9 2 140 6 300 4 19 0.6 32o T-shepe 7 100 2 14 17 3 2 so 160 10 300 2 8 12 2 2 60 140 1 See the following- No. 2 produces a quench air stream parallel to the fiber axis. N o. 4 produces a cyclonic flow pattern around the fiber axis. It will be apparent to those skilled in the art that vari- R f n s Cited ous other modifications within the spirit and scope of 40 UNITED STATES PATENTS the invention are possible. For instance, while the invention is of particular advantage in connection with melt gnvott et 264168 X ragford 264----171 X spinning, the differential thermal or thermal-chemical 3 408 277 10/1968 Martin et a1 2,64 171 X treatment on which this invention is based may also be 3:408:433 10/1968 Bragford 264 168 X applied in solution spinning, 1.e., by sub ecting two parts 2,932,062 4/1960 Speakman et F of the same polymer solution to different degradation 3 095 07 7 19 3 Cobb 18 85 F treatments. The invention should not be deemed to be 3,154,336 11 19 4 Hoag et 1 2 7 UX limited by what has been shown and described herein by 3,161,914 12/1964 Bl mfield et a], 264-171 way of illustration, except as particularly pointed out in 3,209,402 10/ 1965 Riley et al. 18-8 the appended claims. 3,217,734 11/ 1965 Fitzgerald 264--171 X What is claimed 3,259,938 7/1966 Martin 18-85 F 1. Process for producing crimped conjugate filaments gamer 2648171 from a single stream of molten fiber tforming polyester ynum e a 1 8 comprising dividing said single molten stream into a least FOREIGN PATENTS two portions subjecting at least one of said portions to 969,110 9/1964 Great Britain 264-471 chemically different media to alter the melt Viscosity of 1, 0,793 11/1965 France 264--168 the polyester stream by reacting with said chemical media 1,431,147 1/1966 France 264-168 and jointly extruding said polymer portions to form JAY WOO, Primary Examiner unitary filament containing said polymer portions.

US. Cl. X.R.

2. Process for producing crimped conjugate filaments from a single stream of molten fiber forming polymer