US3408251A - Tows of synthetic filaments and method for making the same - Google Patents

Tows of synthetic filaments and method for making the same Download PDF

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US3408251A
US3408251A US424563A US42456365A US3408251A US 3408251 A US3408251 A US 3408251A US 424563 A US424563 A US 424563A US 42456365 A US42456365 A US 42456365A US 3408251 A US3408251 A US 3408251A
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Prior art keywords
tow
filaments
breaking
rollers
snap
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US424563A
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Davies Stanley
Evans Vincent Leighton
Watt John David
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Celanese Corp
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Davies Stanley
Evans Vincent Leighton
Watt John David
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    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01G—PRELIMINARY TREATMENT OF FIBRES, e.g. FOR SPINNING
    • D01G1/00—Severing continuous filaments or long fibres, e.g. stapling
    • D01G1/06—Converting tows to slivers or yarns, e.g. in direct spinning
    • D01G1/08—Converting tows to slivers or yarns, e.g. in direct spinning by stretching or abrading
    • D—TEXTILES; PAPER
    • D02—YARNS; MECHANICAL FINISHING OF YARNS OR ROPES; WARPING OR BEAMING
    • D02J—FINISHING OR DRESSING OF FILAMENTS, YARNS, THREADS, CORDS, ROPES OR THE LIKE
    • D02J1/00—Modifying the structure or properties resulting from a particular structure; Modifying, retaining, or restoring the physical form or cross-sectional shape, e.g. by use of dies or squeeze rollers
    • D02J1/22—Stretching or tensioning, shrinking or relaxing, e.g. by use of overfeed and underfeed apparatus, or preventing stretch
    • D02J1/227—Control of the stretching tension; Localisation of the stretching neck; Draw-pins
    • D—TEXTILES; PAPER
    • D02—YARNS; MECHANICAL FINISHING OF YARNS OR ROPES; WARPING OR BEAMING
    • D02J—FINISHING OR DRESSING OF FILAMENTS, YARNS, THREADS, CORDS, ROPES OR THE LIKE
    • D02J1/00—Modifying the structure or properties resulting from a particular structure; Modifying, retaining, or restoring the physical form or cross-sectional shape, e.g. by use of dies or squeeze rollers
    • D02J1/22—Stretching or tensioning, shrinking or relaxing, e.g. by use of overfeed and underfeed apparatus, or preventing stretch
    • D02J1/228—Stretching in two or more steps, with or without intermediate steps
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
    • Y10T428/2913—Rod, strand, filament or fiber
    • Y10T428/2922—Nonlinear [e.g., crimped, coiled, etc.]
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
    • Y10T428/2913—Rod, strand, filament or fiber
    • Y10T428/2933—Coated or with bond, impregnation or core
    • Y10T428/2964—Artificial fiber or filament
    • Y10T428/2967—Synthetic resin or polymer
    • Y10T428/2969—Polyamide, polyimide or polyester

Definitions

  • This invention relates to improvements in or relating to tow and to a method of producing the same, the said tow consisting of filaments of a polyamide, and is particularly concerned with tow which is intended to be converted into slivers and spun into Schappe-type yarns.
  • Tows such as 100,000 denier 1 /2 denier per filament 66 nylon tow, intended for the production of Schappetype yarns are converted into slivers on a stretch-break- :ing machine and the slivers then processed into the spun yarn.
  • a typical stretch-breaking machine is the Seydel- V stretch-breaking machine the essential parts of which are briefly described below.
  • the Seydel stretch-breaking machine consists essentially of two sections, a stretching section and a breaking section. Nearly all of the stretching is done in the stretching section between the various heads of the machine of which there are normally six.
  • Each of these. heads consists of a series of rollers in a 3 over 4 arrangement in which there are four positively driven steel rollers with three plastic-covered jockey rollers in the intermediate gaps. The tow is laced through these rollers such that it passes under each of the four steel rollers and over each of the three jockey rollers in succession.
  • the surface speed of the driven rollers in any one head is the same, but the surface speed of the rollers in the different heads increases from the feed (creel) to the delivery end of the machine.
  • the breaking section consists of two pairs of rollers
  • the intermediate rollers consist of a positively driven steel roller and a rubber-covered pressure roller, and the front pair of rollers a positively driven steel bottom roller and a leather or rubber-covered top pressing roller.
  • the pressure exerted by the rollers is about 400 lb. and 2,500 lb. respectively.
  • the path of a single tow through the machine is called a channel and the machine may be designed to enable it to take four channels simultaneously.
  • snap breaking occurs particularly when restarting the machine following a voluntary or involuntary stoppage, although 3,408,251 Patented Oct. 29, 1968 ice 2 it may also occur during apparently normal running.
  • the snap-break occurs in the stretching section of the machine and results in all of the filaments in one channel of the tow breaking so that the restringing of that tow is necessary. Since the restringing requires that the machine be stopped, there is the possibility that a snap-break will occur in one of the other channels of two-on restart.
  • Interfilament adhesion increases (a) along the length of the tow in the stretching section and'(b) when the tow is stationary in the machine e.g. during a stoppage.
  • the physical factors involved are the tension in the tow due to stretching, the'normal pressure of the rollers against the tow and the pressure at the nips between the rollers in each head.
  • the increasing tension in the t-owas it travels through the stretching section produces increasing normal and nip pressure as it passes around the rolls.
  • These tensions and pressures are sufficiently great to deform the filaments from circular to hexagonal crosssection and sometimes to cause fusion.
  • These hexagonal filaments will give an increased surface area of interfilament contact and therefore increase the risk of adhesion.
  • Filament adhesion binds the tow either partially or completely into a solid ribbon.
  • Damage to the filaments between the roller nips introduces a line of weakness across the tow. If one or more of the filaments across this line break soon after restart the relatively unchanged total stress acting on the remaining filaments in the ribbon is excessive and causes more filament breakage. Breakdown of the tow is then rapid and a snap-break frequently occurs.
  • Filament adhesion is thought to be the most important factor since a snap-break would be initiated by the weaker filaments in the solid ribbon irrespective of the method of weakening these filaments.
  • a tow should have a low breaking load and a wide spread of physical properties, particularly filament extensibility.
  • the low breaking load enables lower tensions being used in the stretching section of the stretch'breaking machine and thus leads to less interfilament adhesion and nip damage, since the lower the tension the lower the pressure at the nip between the rollers.
  • a lower tension in the tow means that a smaller percentage of filaments need to be broken in the stretching section to prevent slippage at the front rolls in the breaking section of the stretch-breaking machine.
  • a wide range of filaments extensibilities enables the less extensible filaments to be broken in the stretching section and the strength of the tow reduced before the breaking point for the other filaments has been reached.
  • the snap-break rating of a tow on a Seydel stretchbreaking machine is determined in the following manner.
  • the overall draft of the stretching section is adjusted so that no tow slippage occurs between the rollers of the breaking section.
  • Four tow channels are used and ten restarts made after voluntary machine stoppages of f: 1; '73 -5'minutes duration giving ery speed of the tow is set; at 96 ft./min. at a breaking section draft of 1.8 and the tests carried out at an ambient temperature of. 78 F. anda relative humidity of 60%. ;.
  • the snap-breakrating is then calculated from the expres- .sion i ⁇ Percent rating; a
  • a .squirrel cage may be described as an array of bright chrome bars arranged so that the tow can be interlaced through the bars to insert tension in the tow.
  • the draw-crimper draw ratio has to .be reduced to prevent breakage of the filaments either in the squirrel cage or in the drawing zone of the drawcrimper.
  • the resulting crimped tow contains filaments .,drawn to difierent degrees and hence having a range of filament extensibilities.
  • Aa tow having a suitably 10w breaking load, preferably less than 500 kg./ 100,000 denier, can be obtained by's'pin- .ning the" filamentsconstituting the tow from asynthetic 'high molecular weight polymer, e.g. polyhexamethylene liadipamide, having a relative viscosity (R,.V.) of 30 or less and preferably in the range 27-30.
  • R,.V. relative viscosity
  • Relative viscosity of a polyamide is defined as being the ratio of the viscosityof a solution thereof in ninety percent by weight formic acid containing 11 grams'of polyamide per 100 ml. of solution at C., to the viscosity of ninety'percent'formic acid at the same temperature.
  • the increase in the range of filament extensibility required in a tow for it to have a good snap break rating can be'defined by reference to the load extension curve of the tow.
  • a typical load extension curve for a normal tow consisting of polyhexamethylene adipamide filaments ' is shown in the drawing curve A in which L is the breakingload in kg., i.e. the maximum load achieved during extension, and S is the length of the tail of the load-extension curve.
  • the tail S is defined as being the extension in centimeters required to reduce the load from 200 to 25 kg. In order to have an improved snap-break performance the length of the tail should be at least l cm.
  • ingthe tow are xtrudedfrom apolya'rnidehaying'a relative viscosity of 30.0 ⁇ ; less andare subjected toatleasttwo different levels of tension in the squirrel icage of a drawcr'iniping *riiachine and are then 1 drawnand-crimped according to known proc edures. 7
  • a tow consistingofpolyamide filaments produced by the above-mentioned process having a snap break-rating'(as hereinbefor'e defined)..'of less than 10 and having a load extension curve in the tail (ashereinbefore defined) isjat least 1 .cm. longer than the tail of the load extension curve of a tow in which. all the filaments the draw crimping machine.
  • Example 1 1 v A 100,000 denier. tow comprising 11 bundles of fila ments of polyhexamethylene adipamide (each filament being of 1 /2 denier) spun-from polymer having a relative viscosity (R.V.) of 27 is passed into the squirrel cage of a conventional draw-crimpingmachine. Five bundles of filaments are passed around the guide bars at a sufficiently high'angle of wrap to'cause drawing to occur at this stage,
  • the resultant tow had a snap-break rating of 3 when processed on a Seydel stretch breaking machine.
  • the load ex tension curve for the tow had a tail Set 3.4 ems-An identical tow processed in the same way except that all the bundles of filaments were subjected to the same tension in the squirrel cage and the tow drawn using a draw ratio of 3.0,ha'd a snap-break rating of- 98 and the loadextens'ionIcurve had a tail S of 1.5 cm., i.e. 1.9 cm. shorter than-the tow processed according to the invention.
  • Example 2 Two tows identical to those employed in Example -1 were similarly processed but were steam-set for 7 minutes at 25 'p.s.i. 'in a Sanderson steam setting cabinet before testing on the 'Instron tensile tester.
  • the normal tow had a snap-break rating of 87 and a load extension curve having a tail 8 of 1.4 cm s.
  • the tow containing filaments subjected to diiferent levels of tension had a snap-break rating of 4 and atailS to the load extension curve of 2.7 cm.', i.e. 1.3 cms; longer.
  • a process forthe production of a tow suitable for "stretch breaking comprising forming a tow of filaments by extruding said filaments from a polyamide having a relative VISCOSitY of not more than 30, forwarding said tow to the squirrel cage of a draw-crimping machine, subjecting at-least one portion of the filaments forming the tow toa different level of tension in said squirrel cage compared to the'remainder of the filaments of said tow and then'drawing and crimping said tow thereby'producsaid bundles to different levels of tension prior to drawing and drawing, crimping and recombining said bundles into a tow thereby producing a tow of improved stretch breaking characteristics.
  • polyamide is polyhexarnethylene adipamide.
  • a tow comprising a plurality of crimped polyamide continuous filaments wherein said filaments have a breaking load of less than about 500 kg./ 100,000 denier and wherein a proportion of said filaments in said tow has a difierent draw ratio compared to another proportion of filaments in said tow, said tow having a snap-break-rating of less than 10.

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  • Engineering & Computer Science (AREA)
  • Textile Engineering (AREA)
  • Yarns And Mechanical Finishing Of Yarns Or Ropes (AREA)
  • Preliminary Treatment Of Fibers (AREA)
  • Artificial Filaments (AREA)

Description

Get. 29, 1968 5. DAVIES ETAL TOWS OF SYNTHETIC FILAMEN'SS AND METHOD FOR MAKING THE SAME Filed Jan. 11, 1965 I Y g/\\ L I 1 l I O O O O O O O (Move? United States Patent ABSTRACT OF THE DISCLOSURE- A tow and a 'method for'producing said tow which is suitable for stretch-breaking produced by extruding a polyamide having a relative viscosity of less than about 30 into a plurality of filaments whichmake up the tow. The tow is split into a plurality of bundles or sub-tows and each bundle is then subjected to a different tensioning prior to drawing. The bundles are then reformed into the tow and draw-crimped. The resulting tow has an improved snap-break rating and a more desirable load extension curve.
This invention relates to improvements in or relating to tow and to a method of producing the same, the said tow consisting of filaments of a polyamide, and is particularly concerned with tow which is intended to be converted into slivers and spun into Schappe-type yarns.
Tows, such as 100,000 denier 1 /2 denier per filament 66 nylon tow, intended for the production of Schappetype yarns are converted into slivers on a stretch-break- :ing machine and the slivers then processed into the spun yarn. A typical stretch-breaking machine is the Seydel- V stretch-breaking machine the essential parts of which are briefly described below.
The Seydel stretch-breaking machine consists essentially of two sections, a stretching section and a breaking section. Nearly all of the stretching is done in the stretching section between the various heads of the machine of which there are normally six. Each of these. heads consists of a series of rollers in a 3 over 4 arrangement in which there are four positively driven steel rollers with three plastic-covered jockey rollers in the intermediate gaps. The tow is laced through these rollers such that it passes under each of the four steel rollers and over each of the three jockey rollers in succession. The surface speed of the driven rollers in any one head is the same, but the surface speed of the rollers in the different heads increases from the feed (creel) to the delivery end of the machine.
The breaking section consists of two pairs of rollers; the
near pair, referred to as the intermediate rollers, is at the same time the seventh head of the stretching section since it has a higher surface speed than that of the rollers of the sixth head. The intermediate rollers consist of a positively driven steel roller and a rubber-covered pressure roller, and the front pair of rollers a positively driven steel bottom roller and a leather or rubber-covered top pressing roller. In order that these rollers should be enabled to grip the tow sufiiciently tightly to avoid slippage when breaking, the pressure exerted by the rollers is about 400 lb. and 2,500 lb. respectively.
The path of a single tow through the machine is called a channel and the machine may be designed to enable it to take four channels simultaneously.
One of the difiiculties encountered in the use of this type of machine is that of so called snap breaking which occurs particularly when restarting the machine following a voluntary or involuntary stoppage, although 3,408,251 Patented Oct. 29, 1968 ice 2 it may also occur during apparently normal running. The snap-break occurs in the stretching section of the machine and results in all of the filaments in one channel of the tow breaking so that the restringing of that tow is necessary. Since the restringing requires that the machine be stopped, there is the possibility that a snap-break will occur in one of the other channels of two-on restart.
It is believed that major factors in the occurrence of snap-breaks in a tow are interfilament adhesion and filament damage caused by the nipof the rollers in the stretching section of the stretch-breaking machine.
Interfilament adhesion increases (a) along the length of the tow in the stretching section and'(b) when the tow is stationary in the machine e.g. during a stoppage. The physical factors involved are the tension in the tow due to stretching, the'normal pressure of the rollers against the tow and the pressure at the nips between the rollers in each head. The increasing tension in the t-owas it travels through the stretching section produces increasing normal and nip pressure as it passes around the rolls. These tensions and pressures are sufficiently great to deform the filaments from circular to hexagonal crosssection and sometimes to cause fusion. These hexagonal filaments will give an increased surface area of interfilament contact and therefore increase the risk of adhesion. Filament adhesion binds the tow either partially or completely into a solid ribbon.
Damage to the filaments between the roller nips introduces a line of weakness across the tow. If one or more of the filaments across this line break soon after restart the relatively unchanged total stress acting on the remaining filaments in the ribbon is excessive and causes more filament breakage. Breakdown of the tow is then rapid and a snap-break frequently occurs.
Filament adhesion is thought to be the most important factor since a snap-break would be initiated by the weaker filaments in the solid ribbon irrespective of the method of weakening these filaments.
It is a necessary feature in the processing of 100,000 denier nylon tows on the stretch-breaking machine as described above, that a large proportion of filaments are broken in the stretching section in order to reduce the strength of the tow sufficiently to prevent slippage at the front pair of rollers in the breaking section. In a tow having high filament adhesion this deliberate breaking action helps to promote snap-breaking at restart and may also be at least partly responsible for these snap-breaks which occasionally occur during normal running.
We have now found that in order to have a good snapbreak rating, i.e. a minimal tendency to snap breaking, a tow should have a low breaking load and a wide spread of physical properties, particularly filament extensibility. The low breaking load enables lower tensions being used in the stretching section of the stretch'breaking machine and thus leads to less interfilament adhesion and nip damage, since the lower the tension the lower the pressure at the nip between the rollers. Also a lower tension in the tow means that a smaller percentage of filaments need to be broken in the stretching section to prevent slippage at the front rolls in the breaking section of the stretch-breaking machine. A wide range of filaments extensibilities enables the less extensible filaments to be broken in the stretching section and the strength of the tow reduced before the breaking point for the other filaments has been reached.
The snap-break rating of a tow on a Seydel stretchbreaking machine is determined in the following manner. The overall draft of the stretching section is adjusted so that no tow slippage occurs between the rollers of the breaking section. Four tow channels are used and ten restarts made after voluntary machine stoppages of f: 1; '73 -5'minutes duration giving ery speed of the tow is set; at 96 ft./min. at a breaking section draft of 1.8 and the tests carried out at an ambient temperature of. 78 F. anda relative humidity of 60%. ;.The snap-breakrating is then calculated from the expres- .sion i {Percent rating; a
[Number ofsnap=breaks -+tN.umber of veryzthin v places X3)+(Number. ofthin places X1) a -,'.4OX'1O-- s :v
10,..ar1d
40 tests per .sample...'lhe.deli v.-...
preferably less th,anl .;i f thetowto be capable ofjbeing Although a tow havinga limited spread of physical properties, such as extensibility, can be produced by varying the spinning conditions, 'a wider and more significant "spread can be obtained at the draw crimping stage in the production of tow by using various yarn paths in the I squirrel cage'of the draw crimper.
were subjected to the same tension'in thesquirrel cage of For the purpose of this description a .squirrel cage may be described as an array of bright chrome bars arranged so that the tow can be interlaced through the bars to insert tension in the tow.
Thus by increasing the angle of Wrap around the guide bars in the squirrel cage for some of the filaments in the ,tow and therefore increasing the tension in these filaments relatively to the remainder, the more highly tensioned filamentsare stretched or drawn to some extent in the .squirrel cage. Because of the stretching of some 'of the filaments in the tow the draw-crimper draw ratiohas to .be reduced to prevent breakage of the filaments either in the squirrel cage or in the drawing zone of the drawcrimper. The resulting crimped tow contains filaments .,drawn to difierent degrees and hence having a range of filament extensibilities.
Aa tow having a suitably 10w breaking load, preferably less than 500 kg./ 100,000 denier, can be obtained by's'pin- .ning the" filamentsconstituting the tow from asynthetic 'high molecular weight polymer, e.g. polyhexamethylene liadipamide, having a relative viscosity (R,.V.) of 30 or less and preferably in the range 27-30. w
' Relative viscosity of a polyamide is defined as being the ratio of the viscosityof a solution thereof in ninety percent by weight formic acid containing 11 grams'of polyamide per 100 ml. of solution at C., to the viscosity of ninety'percent'formic acid at the same temperature. I
The increase in the range of filament extensibility required in a tow for it to have a good snap break rating can be'defined by reference to the load extension curve of the tow. A typical load extension curve for a normal tow consisting of polyhexamethylene adipamide filaments 'is shown in the drawing curve A in which L is the breakingload in kg., i.e. the maximum load achieved during extension, and S is the length of the tail of the load-extension curve. The tail S is defined as being the extension in centimeters required to reduce the load from 200 to 25 kg. In order to have an improved snap-break performance the length of the tail should be at least l cm. greater than that of an equivalent tow in which all of the bundles of filaments were subjected to the same tension in the squir- -rel cage. The effect on the load extension curve of' forrn- -ing a tow from filaments spun from polymer having an R:V.:'of less than 30 and whichhave been subjected to 'different'tensions in the squirrel'cageis shown by curve B 0f thedrawing- The value of the breaking load, L ,'is lower-and the length of the tail S considerably increased.
thereisip q id s. .suitable for, .stretcl tebreaking ,wherein the. filarn The load extension. curve .is determineiusiuguan. Instron tensile tester (registered trade mark) fitted with special clamps which are described in British patent application No. 937,818. In the test 20 cm. unsupported length of sample is extendedatSO-ctriL/min. Q
j aspect ffthi s ihventio Wherefore, LMQ
ingthe tow are xtrudedfrom apolya'rnidehaying'a relative viscosity of 30.0}; less andare subjected toatleasttwo different levels of tension in the squirrel icage of a drawcr'iniping *riiachine and are then 1 drawnand-crimped according to known proc edures. 7
According to'anoth' r aspect ofthis' invention there is provided a tow consistingofpolyamide filaments produced by the above-mentioned process having a snap break-rating'(as hereinbefor'e defined)..'of less than 10 and having a load extension curve in the tail (ashereinbefore defined) isjat least 1 .cm. longer than the tail of the load extension curve of a tow in which. all the filaments the draw crimping machine.
,Theimproved stretch-breaking performance of tows -p roduced according, to this invention will now. be illustrated by the following examples, which examples are V invno way intended to limit the scope of the invention.
Example 1 1 v A 100,000 denier. tow comprising 11 bundles of fila ments of polyhexamethylene adipamide (each filament being of 1 /2 denier) spun-from polymer having a relative viscosity (R.V.) of 27 is passed into the squirrel cage of a conventional draw-crimpingmachine. Five bundles of filaments are passed around the guide bars at a sufficiently high'angle of wrap to'cause drawing to occur at this stage,
the remaining 6 bundles of filaments are passed through at the normal tension. After passing through the squirrel cage the bundles of filaments are recombined and'drawcrimped using a draw ratioof 2.64 in the usual manner. The resultant tow had a snap-break rating of 3 when processed on a Seydel stretch breaking machine. The load ex tension curve for the tow had a tail Set 3.4 ems-An identical tow processed in the same way except that all the bundles of filaments were subjected to the same tension in the squirrel cage and the tow drawn using a draw ratio of 3.0,ha'd a snap-break rating of- 98 and the loadextens'ionIcurve had a tail S of 1.5 cm., i.e. 1.9 cm. shorter than-the tow processed according to the invention.
Example 2 Two tows identical to those employed in Example -1 were similarly processed but were steam-set for 7 minutes at 25 'p.s.i. 'in a Sanderson steam setting cabinet before testing on the 'Instron tensile tester. The normal tow had a snap-break rating of 87 and a load extension curve having a tail 8 of 1.4 cm s. whereas the tow containing filaments subjected to diiferent levels of tension had a snap-break rating of 4 and atailS to the load extension curve of 2.7 cm.', i.e. 1.3 cms; longer.
What we claim is: j 1. A process forthe production of a tow suitable for "stretch breaking comprising forming a tow of filaments by extruding said filaments from a polyamide having a relative VISCOSitY of not more than 30, forwarding said tow to the squirrel cage of a draw-crimping machine, subjecting at-least one portion of the filaments forming the tow toa different level of tension in said squirrel cage compared to the'remainder of the filaments of said tow and then'drawing and crimping said tow thereby'producsaid bundles to different levels of tension prior to drawing and drawing, crimping and recombining said bundles into a tow thereby producing a tow of improved stretch breaking characteristics.
3. A process according to claim 2 wherein the polyamide has a relative viscosity in the range of 27-30.
4. A process according to claim 3 wherein the polyamide is polyhexarnethylene adipamide.
5. A tow comprising a plurality of crimped polyamide continuous filaments wherein said filaments have a breaking load of less than about 500 kg./ 100,000 denier and wherein a proportion of said filaments in said tow has a difierent draw ratio compared to another proportion of filaments in said tow, said tow having a snap-break-rating of less than 10.
References Cited UNITED STATES PATENTS 2,385,890 10/ 1945 Spanagel. 3,011,215 12/1961 Alley. 3,114,999 12/ 1965 Coggeshall.
ROBERT F. BURNETT, Primary Examiner.
L. M. CARLIN, Assistant Examiner.
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3846881A (en) * 1972-01-05 1974-11-12 Phillips Petroleum Co Filament crimping

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2385890A (en) * 1943-03-31 1945-10-02 Du Pont Spinning process
US3011215A (en) * 1959-01-29 1961-12-05 Du Pont Process for removing non-uniformities in undrawn synthetic filaments
US3114999A (en) * 1960-11-28 1963-12-24 Monsanto Chemicals Method and apparatus for treating and drawing synthetic filament yarns

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2385890A (en) * 1943-03-31 1945-10-02 Du Pont Spinning process
US3011215A (en) * 1959-01-29 1961-12-05 Du Pont Process for removing non-uniformities in undrawn synthetic filaments
US3114999A (en) * 1960-11-28 1963-12-24 Monsanto Chemicals Method and apparatus for treating and drawing synthetic filament yarns

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3846881A (en) * 1972-01-05 1974-11-12 Phillips Petroleum Co Filament crimping

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