U.S. patent number 3,769,787 [Application Number 05/192,081] was granted by the patent office on 1973-11-06 for compact multi-filament textile yarn and method of making the same.
This patent grant is currently assigned to Hartford Fibres Ltd., Hartford Spinning (Canada) Ltd.. Invention is credited to Abraham J. Rosenstein, Nathan Rosenstein.
United States Patent |
3,769,787 |
Rosenstein , et al. |
November 6, 1973 |
COMPACT MULTI-FILAMENT TEXTILE YARN AND METHOD OF MAKING THE
SAME
Abstract
The filaments of multi-filament synthetic textile yarn are
rendered and maintained sufficiently coherent and compact for
high-speed fabricating purposes such as knitting, winding and
weaving by continuously disposing special wrapper filaments in
generally helical paths around the core filaments of the yarn, at
least one such wrapper filament being disposed in a clockwise
manner and another wrapper filament counter-clockwise. The wrapper
filaments (drawn or undrawn) are continuously applied from over the
ends of supply packages, or at the spinneret or otherwise, and if
undrawn may be drawn concurrently with the core filaments.
Inventors: |
Rosenstein; Nathan (West
Hartford, CT), Rosenstein; Abraham J. (West Hartford,
CT) |
Assignee: |
Hartford Spinning (Canada) Ltd.
(Kingston, Ontario, CA)
Hartford Fibres Ltd. (Kingston, Ontario, CA)
|
Family
ID: |
22708159 |
Appl.
No.: |
05/192,081 |
Filed: |
October 26, 1971 |
Current U.S.
Class: |
57/227; 57/6;
57/228; 57/7; 57/310 |
Current CPC
Class: |
D02G
3/385 (20130101) |
Current International
Class: |
D02G
3/38 (20060101); D02g 003/26 (); D02g 003/38 () |
Field of
Search: |
;57/3,6,7,13,14,15,16-18,34R,36,139,14R,144,149,153,156,157R,160,162 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
1,412,441 |
|
Aug 1965 |
|
FR |
|
1,926 |
|
May 1878 |
|
GB |
|
Primary Examiner: Watkins; Donald E.
Claims
The following is claimed:
1. Compact yarn comprising a plurality of flexible continuous core
filaments having substantially zero twist wrapped in coherent
fashion under low tension by flexible wrapper filaments spirally
arranged about and in contact with said core filaments, the number
of core filaments being greater than the number of wrapper
filaments, at least one of said wrapper filaments being arranged in
a clockwise direction and at least another in a counterclockwise
direction, said wrapper filaments being composed of continuous
filament synthetic polymeric material, and one such wrapper
filament being spiraled over the exterior of said core filaments
and repeatedly and successively over another wrapper filament as
well.
2. The yarn defined in claim 1 wherein said core filaments are
continuous filaments of synthetic polymeric material.
3. The yarn defined in claim 2 wherein at least the majority of
said core filaments and at least the majority of said wrapper
filaments are composed of essentially the same synthetic polymeric
material.
4. The yarn defined in claim 1 wherein said wrapper filaments are
composed of undrawn synthetic organic material.
5. The yarn defined in claim 1 wherein both said wrapper filaments
and said core filaments are composed of undrawn synthetic organic
material.
6. The yarn defined in claim 1 wherein the yarn has a denier of
about 10 to 10,000.
7. The yarn defined in claim 1 wherein the wrapper filaments
comprise numerically about 1 percent - 20 percent of the total
filaments of the yarn.
8. The yarn defined in claim 1 wherein the core filaments and the
wrapper filaments are closely adjacent and randomly tangled.
9. The yarn defined in claim 1 wherein the core filaments and the
wrapper filaments are twisted about the yarn axis.
10. The yarn defined in claim 5 wherein said core filaments are
continuous filaments.
11. The yarn defined in claim 1, wherein the core filaments are
crimped undrawn, and are subsequently heat set.
12. The yarn defined in claim 1, wherein the wrapper filaments are
wrapped about said core filaments at substantially zero
tension.
13. The yarn defined in claim 1, wherein the wrapper filaments
comprise numerically about 2 percent to 10 percent of the total
filaments of the yarn.
14. In a method of making a compact yarn, the steps which comprise
continuously feeding a multiplicity of drawable continuous
synthetic core filaments along a predetermined path, continuously
applying a continuous synthetic drawable wrapper filament in a
spiral manner around the core filaments, continuously applying
another continuous synthetic drawable wrapper filament in a counter
spiral manner around the core filaments plus the wrapper filament
previously wrapped, and drawing the resulting yarn.
15. The method defined in claim 14, wherein the core filaments are
crimped prior to the application of the wrapper filaments.
16. The method defined in claim 14, wherein the core filaments are
dyed prior to the application of the wrapper filaments.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to the art of making multiple filament yarn
coherent and compact, as distinguished from the bulky or fluffy
products that are generally referred to as texturized yarns.
The invention relates particularly to yarn which, even at
substantially zero twist, is sufficiently compact for normal
high-speed handling in textile fabricating machinery such as
machines for winding, knitting, weaving and braiding, for example,
but which does not have the high cost of twisted yarns or
air-entangled yarns which are currently in use for those purposes.
Yarn according to this invention may, however, be subjected to
subsequent twisting if this should be dsired for any special
purpose.
It is well known that synthetic continuous filament yarns, produced
in multiple filament form in a spinneret and subsequently drawn,
are not often suitable for knitting, weaving or other fabricating
uses without having been subjected to some treatment which causes
the individual filaments of the yarn to become coherent and compact
during the fabricating operation. Otherwise, stray filaments tend
to snag and break or contact with fabricating machinery in a manner
to form slubs, wraps and the like which are very costly to the
fabric producer.
It has, therefore, become conventional in some operations to
provide the yarn in the form of a compact filament bundle for
high-speed operations by subjecting the yarn to a separate twisting
operation. While twisted yarn is in commercial use in large volume
today, the extra cost of the separate twisting operation is quite
substantial and significantly increases the cost of the fabricated
product.
It has also been proposed to make the filaments of zero twist yarn
compact by running the yarn through a sizing bath and drying the
sized yarn product. The size acts in the manner of an adhesive and
maintains the compactness of the filaments in many successful
high-speed operations. However, the cost of the sizing material and
of the separate sizing operation significantly increases the cost
of the fabric product, and it is often necessary for many purposes
to subject the resulting fabricated product to an additional
washing operation in order to remove the size material from the
fabric.
It has also been proposed to subject the filaments of the yarn to a
tangling operation so that they retain their compactness during the
high-speed fabricating operations. The patent to Bunting et al.
U.S. Pat. No. 2,985,995, for example, discloses various forms of
air jet devices which are stated to produce a compact yarn composed
of filaments at least some of which are randomly interlaced with
one another. The continuous use of compressed air, in the
quantities that have been found to be necessary for many
conventional types of yarn, adds very considerably to the cost of
the interlaced yarn product and of the fabrics into which it is
made.
The invention also relates to methods of making a compact, coherent
zero twist yarn continuously and economically at a high production
rate.
It is also known to make a composite yarn by helical wrapping about
a core yarn (Kosaka et al. U.S. Pat. No. 3,438,193) and to wrap
helically in general (Nalpas et al. U.S. Pat. No. 3,439,484, Cannon
U.S. Pat. No. 1,732,593).
With respect to metallic monofilaments, it has also been known to
form helical wraps around copper wire, for example, to provide an
intervening layer between the copper wire and its insulation. In
such cases, however, the copper wire has been a thick, heavy
monofilament and there has been no problem with respect to any
cohesion of multiple filaments, or any other problem which is
analagous to the problems present in connection with this
invention.
So far as is known, however, the art has never suggested that such
fragile elements as synthetic thermoplastic polymeric filaments
could be helically wrapped about a bundle of such filaments without
undergoing excessive breakage, or that this would have any benefit.
Further, it would be expected normally that the difficulties
encountered with tow would be magnified many times if attempts were
made to wrap fragile filaments around core filaments to make a
yarn.
Accordingly, it is an object of this invention to provide a
multi-filament yarn product and a method of making the same, having
particular advantage in the textile industry.
SUMMARY OF THE INVENTION
It has been discovered that, when a multi-filament yarn core, which
filaments may be arranged at zero twist or twisted, is subjected to
wrapping in a generally helical manner with at least a pair of
individual filaments one arranged helically in a clockwise manner
and the other arranged helically in a counter-clockwise manner,
such filaments being applied to the core preferably under low
tension, a yarn is created which is sufficiently compact that it
can readily be fed into a fabricating machine and knitted, woven or
braided, for example, or wound onto a package or bobbin or stored
otherwise as a yarn and later withdrawn and used without causing
tangling or intermingling of individual filaments. Further, the
yarn may be made in such a way that it is sufficiently open that it
is particularly receptive to dyeing or to treatment in aqueous or
other baths, and may be advantageously and economically dried
thereafter.
Yarn according to this invention may be manufactured advantageously
of continuous polymeric filaments which can be formed in the
undrawn state and then subseqently drawn. For example, the wrapper
filaments may be composed of undrawn filaments in the form of a
package containing very large numbers of turns arranged around a
central opening, as in a bobbin, pirn, beam or the like, so
arranged that the core filaments are drawn through the central
opening and the wrapper filaments are helically arranged by drawing
them endwise off the coil so that the coil configuration causes the
nautral formation of the helical arrangement about the core
filaments.
On the other hand, the core filaments may be spun from a melt spin
bath or otherwise, using a conventional spinneret, thus producing a
large number of undrawn, parallel core filaments. Undrawn wrapper
filaments may then be arranged about the core filaments, by
providing rotating spinnerets which surround the stationary
spinneret through which the core filaments were created, thus
wrapping the wrapper filaments continuously helically about the
core filaments freshly as they are formed.
It is particularly advantageous that undrawn core filaments and
undrawn wrapper filaments, having thus been formed into compact
undrawn yarn, can be fed directly into a series of draw rolls in
such a manner that all of these filaments are drawn together and
concurrently as a unitary yarn.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
This invention is directed to a yarn which consists of multiple
filaments, wherein the core filaments very substantially outnumber
the wrapper filaments. One typical yarn to which this invention has
been very advantageously applied has been a nylon yarn of 70 denier
in which 30 core filaments are maintained in compact form by four
wrapper filaments, two clockwise and two counter-clockwise, wrapped
at 1/8 turn per inch, therefore producing a 70-denier 34-filament
product. Other examples include a polyester yarn of about 1,000
denier, 15 denier per filament, composed of 59 core filaments and
18 wrapper filaments (nine and nine). Other yarns for which the
invention is ideally suited include nylon multi-filament yarns of
denier from about 10 to about 5,000 and even to industrial yarns
having deniers of 10,000 and above, and various yarns of all known
multi-filament synthetic materials including polyamides, e.g.,
poly(epsilon caproamide) and poly(hexamethylene adipamide);
cellulose esters, e.g. cellulose acetate; polyesters, particularly
polyesters of terephthalic acid or isophthalic acid and a lower
glycol, e.g., poly(ethylene terephthalate),
poly(hexahydro-p-xylylene terephthlate); polyalkylenes, e.g.,
polyethylene, linear polypropylene, etc.; polyvinyls and
polyacrylics, e.g., polyacrylonitrile, as well as copolymers of
acrylonitrile and other copolymerizable monomers, and various other
synthetic continuous filament materials, regardless of denier per
filament and regardless of the cross-section or total denier of the
yarn, provided that the core filaments outnumber the wrapper
filaments.
The filaments may have a wide variety of cross-sections in addition
to the usual circular cross-section, for example elliptical,
Y-shape, triangular, heart-shape, square, etc.
Other typical yarns for which this invention is effective appear in
the following table:
---------------------------------------------------------------------------
Wrapper Filaments clockwise/ Yarn Core counter Composition Denier
Fila- Fila- clock- ments ments wise
__________________________________________________________________________
Polyethylene tere- 70 34 32 1/1 phthalate " 70 34 30 2/2 " 70 34 26
4/4 " 70 34 20 7/7
__________________________________________________________________________
Cellulose acetate 150 40 36 2/2 " 150 40 30 5/5 (plied) " 150 40 24
8/8 (plied)
__________________________________________________________________________
Cellulose acetate 75 24 20 2/2 " 75 24 18 3/3 " 75 24 16 4/4 " 75
24 14 5/5
__________________________________________________________________________
Nylon 6-6 70 2/2 34 32 1/1 " 70 34 30 2/2 " 70 34 24 5/5 " 70 34 24
6/4 " 70 34 18 8/8
__________________________________________________________________________
Nylon 6-6 50 17 15 1/1 " 50 17 13 2.2 " 50 17 11 3/3 (plied)
__________________________________________________________________________
Cellulose acetate 300 80 70 5/5 " 300 80 60 10/10 " 300 80 50 15/15
__________________________________________________________________________
Many other yarns, deniers, and filament arrangements may be used.
However it is usually important in accordance with this invention
that multiple filaments of the yarn product are arranged in a
generally helical manner and of opposite hand about the core
filaments. The filaments may be applied singly or, if preferred,
doubled.
In applying the wrapper filaments to the core, a controlled amount
of tension may be imposed, but it has been discovered that a tight
wrap is usually unsatisfactory because of danger of breakage of the
wrapper filaments, particularly if they are drawn filaments and
even if they are plied. For that reason, substantially zero tension
is preferably applied to all filaments when they are in the process
of being helically wrapped around the core filaments.
Numerically, the total clockwise and counter-clockwise wrapper
filaments may be as low as about 1 percent of the total yarn, up to
as high as about 40 percent, preferably in the range of about 1
percent - 20 percent, and even more preferably about 2 percent - 10
percent.
DRAWINGS
FIG. 1 shows schematically an alternate form of apparatus for
making continuous filament yarn according to this invention;
FIG. 1(a) is a sectional view taken as indicated by the lines and
arrows I(a) -- I(a) which appear in FIG. 1;
FIG. 2 is an enlarged view of a length of yarn, shown broken off at
the ends, constructed and arranged in accordance with features of
this invention, with the ends of some of the wrapping filaments
shown broken off at random in order to illustrate the nature of the
wrap more clearly;
FIG. 3 shows a modification of a portion of the apparatus appearing
in FIG. 1, wherein the filament package may be rotated positively
and controllably in a manner to magnify and control the helix
angles of the wrapper filaments;
FIG. 4 of the drawings shows schematically a spinning apparatus and
method which advantageously causes the formation of a continuous
filament yarn embodying features of this invention;
FIG. 5 is a sectional view taken as indicated by the lines and
arrows V -- V which appear in FIG. 4;
FIG. 6 is an enlarged view, showing a modified spineret arrangement
useful in the practice of this invention; and
FIGS. 7 and 8 are sectional views taken as indicated by the lines
and arrows VII -- VII and VIII -- VIII, respectively, which appear
in FIG. 6.
Turning now to FIG. 1, the number 10 designates a conventional melt
spin tank and the number 11 designates a conventional spinneret
which is connected to the tank in a manner to create a multiplicity
of substantially parallel core filaments C. The core filaments C,
without any wrapper filaments, are passed about a guide roll 30 for
the purpose of assembling them with clockwise and counterclockwise
wrapper filaments. A support 31 is provided carrying a yarn package
32 having a central opening 33 through which the core filaments are
conducted. Filaments, preferably undrawn, are wrapped on the
package 32 in such a manner that, when the filaments F.sub.1 are
taken off the yarn package 32 in an endwise manner as shown in FIG.
3, the wrapper filaments are automatically wrapped in a clockwise
direction about the core filaments C. This yarn package 32, as
shown, is stationary and contains a very large poundage of fine
filaments, such that very great lengths of core filaments can be
run through and wrapped in a continuous manner for the yarn package
32.
Another yarn package 34 is provided on a support 35, which is
preferably similar to the yarn package 32 but is arranged in such a
manner that the filaments F.sub.2 are wrapped in a counterclockwise
direction about the core filaments and about the clockwise
filaments that have been wrapped about the core filaments in the
immediately preceding step. The number 36 designate the rolls of a
draw frame 37, in which the core filaments, the counter-clockwise
wrapper filaments and the clockwise wrapper filaments are all drawn
concurrently and in the same operation. This drawing step may be
applied to the compact yarn according to this invention in
essentially the same manner in which it is applied to conventional
undrawn yarns.
FIG. 1(a) is an end view showing the package of counterclockwise
wrapper filaments, with the main bundle of filaments and the
counter-clockwise filaments passing through the central opening
thereof.
Accordingly, it will be observed that when the filaments are taken
off the end of the package 32 they are continuously wrapped
helically in a clockwise manner and similarly the filaments taken
off the filament package 34 are arranged in a counter-clockwise
manner, and this continues automatically so long as the delivery
rolls 36 continue to draw upon the compact yarn thus created. There
is no practical limit to the number of filament packages that may
be utilized, but it is preferred to space the filament packages
longitudinally along the length of the core filaments, so that
spaces exist between the various filaments in the positions they
occupy after they are applied to the core.
A preferred manner of starting up the apparatus of FIG. 1 is to
provide substantially equal lengths of filaments on each filament
package, 32 and 34, and to start up the spinneret in the usual way,
hand-wrapping the wrapper filaments around the freshly made core
filaments until sufficient length of wrapped, coherent yarn is
provided so that the take-up device 46 takes up not only the core
filaments but the spirally wrapped filaments as well. Then, by
simply operating the drive of the take-up devices 36, 46, both the
core filaments and all of the wrapper filaments are automatically
moved as a unit in a longitudinal direction. Suitable contact may
be provided at the spinneret in the usual manner.
FIG. 2 shows a length of compact yarn produced in accordance with
this invention, showing the relatively large number of core
filaments C, together with wrapper filaments F.sub.1 which are
arranged generally helically in a clockwise manner and wrapper
filaments F.sub.2 which are arranged generally helically in a
counter-clockwise manner.
FIG. 3 shows a support 40 for a package 41 of wrapper filaments,
mounted on bearings 42 and provided with a pulley 43 driven by a
belt 44 powered by a motor 45 in a manner to provide positive
rotation to the package of wrapper filaments. Means are provided
(such as a conventional rheostat, not shown) for changing and
adjusting the speed of the motor 45, thus adjusting and controlling
the speed of rotation of the wrapper filaments package 41, thus
adjusting the helix angle of wrap ( .theta., see FIG. 2) of the
wrapper filaments.
Normally, it is not necessary to apply special tension to the
wrapper filaments and low tension is desirable in order to
eliminate breakage. It is, of course, possible to apply special
tension devices to the filaments as they pass from the packages to
the core, to provide a controlled tension for each wrapper
filament. Also, for any specific purpose, it may be possible to
apply more tension to one filament than to another filament, and
each may be applied at an individual, controlled tension.
Preferably at least two closely adjacent production lines are
provided, each using an apparatus of the general type shown in FIG.
1, each including an aligned series of filament bobbins or packages
like the packages 32, 34. Change-over is readily effected with such
two production lines, the second production line being maintained
in a condition ready to operate and provided with fresh packages of
counter-clockwise and clockwise filaments whenever the packages on
the first production line are about to become depleted. At a given
moment, the operator can simply grasp the filament core as it
approaches the entrance of one production line and switch it over
to the other production line by inserting it into the central
opening in the first filament package in the alternate production
line. By any convenient means well known in the textile industry,
such as a conventional air aspiration tube or stream, for example,
the core is forced through the opening at the center of the
clock-wise package and then through the opening at the center of
the counterclockwise package, the filaments from each are coupled
by hand with the core, and operation is continued essentially
without interruption.
Referring now to FIG. 4, it will be seen again that a tank 10 of
the usual sort is provided for containing the melt spin liquid,
which may be any of the well known melt spin baths conventionally
used in the manufacture of synthetic filaments such as nylon,
polypropylene, polyethylene, cellulose acetate or the like, all of
which are in such form that they can be passed through the holes of
spinnerets and thus be formed into solid filaments. The melt spin
bath is normally maintained under positive pressure by injection of
nitrogen gas or by other conventional means. At a suitable location
is a stationary spinneret 11 which is provided with a substantial
plurality of tiny holes through which the liquid from the melt spin
bath may flow, to form a multiplicity of core filaments C.
Arranged concentrically about the stationary spinneret 11 is a ring
spinneret 12 which is also arranged to receive liquid under
pressure from the melt spin bath in the tank 10, and which is
provided with a relatively small number of holes for the formation
of wrapper filaments adapted to be arranged clockwise about the
core filaments C.
Means are provided for rotating the ring spinneret 12 in a
clockwise direction, including a motor 13 and a gear train 14.
Arranged concentrically with and outside of the ring spinneret 12
is another ring spinneret 16 arranged to rotate in a
counter-clockwise direction about the stationary spinneret 11. The
ring spinneret 16 is also connected to receive liquid under
pressure from the melt spin bath in the tank 10, and is arranged to
distribute a small number of wrapper filaments in a
counter-clockwise direction around the relatively larger number of
filaments in a core C. A motor 15 may be used conveniently to drive
the ring spinneret 16 in a counter-clockwise direction, utilizing a
gear train 17.
Pressure seals 19 are provided between the melt spin tank 10 and
the rotating spinnerets 12 and 16, permitting rotation of the
spinnerets without leakage of the pressurized fluid. Although FIG.
4 shows the pressurized seals in perhaps their most simple form, no
effort has been made to illustrate the precise details of the
rotating seals since various types of such seals, themselves well
known in the art, may be used.
Means are provided for solidifying the filaments created in the
spinnerets 11, 12 and 16, as by providing an elongated heated air
space 20, in a manner well known in the synthetic spinning field.
In FIG. 4 a guide roll 21 is shown, around which the solidified and
assembled but undrawn yarn is trained, in a manner to conduct the
yarn to the draw rolls 18.
FIG. 5 shows that the spinnerets 12 and 16 are arranged
concentrically about the stationary spinneret 11 for the purpose of
concurrently creating the core filaments, the counter-clockwise
wrapper filaments and the clockwise wrapper filaments.
A convenient manner of starting up the apparatus of FIG. 4 is to
start up all of the spinnerets 11, 12 and 16 without rotating
spinnerets 12 or 16, and to run for a convenient period of time
with the "wrapper" filaments parallel to the core filaments, and
then to start rotating the inner and outer rotating ring spinnerets
12 and 16. Once operation has been begun, it can be continued
without interruption by simply maintaining a proper supply of
pressurized liquid in the melt spin bath in the tank 10 and
supplying such liquid to the spinnerets 11, 12 and 16.
FIGS. 6 - 8 show a modified form in which the need for slidable
pressure seals is eliminated. As heretofore described, a main tank
10 is provided for supplying the pressurized melt spin fluid to the
central spinneret 11. However a supplemental melt spin tank 60 is
mounted on rollers 61 on top of tank 10. Tank 60 has an inner wall
62 creating an open central space 63 housing a drive shaft 64 and,
see particularly FIG. 7, pinion 65, gear 66 and ring gear 67
through which the entire tank 60 is driven in rotation in the
direction indicated by the arros (a) in FIG. 7.
Another supplemental melt spin tank 70 is mounted on rollers 71 on
top of tank 60. Tank 70 has an inner wall 72 creating an open
central space 73 housing the same drive shaft 64 and, see
particularly FIG. 8, pinion 74 and ring gear 75 through which the
entire tank 70 is driven in rotation in the direction indicated by
the arrow (b) in FIG. 8, opposite to the direction of rotation of
tank 60.
Drive shaft 64 is power driven by motor 80.
Connected into tank 60 is a rigidly hung pressure pipe 81 from
which the planetary spinneret 12 is hung. Similarly, a rigid
pressure pipe 82 is connected to tank 70 and extends at a location
spaced outwardly of pipe 81 down to a location below spinneret 12,
where planetary spinneret 16 is attached to pipe 82.
It will be apparent that the pipe 81 and attached planetary
spinneret 12 are driven continuously in rotation in a given
direction (say clockwise) around the core filaments C, thus
applying one or more wrapper filaments continuously in that
direction, and that planetary spinneret 16 revolves in the opposite
direction, applying one or more wrapper filaments in the opposite
direction.
Since the spinnerets 12, 16 are sealed in a fixed manner to pipes
81, 82 and since those pipes are scaled in a fixed manner to their
respective tanks, there is no need to use or to maintain or replace
any sliding pressure seals of the type shown in FIG. 4 and the
apparatus is capable of operating in a continuous manner for a
virtually indefinite period of time by merely continuously feeding
the melt spin fluid to the main tank 10 through the feed pipes 85,
86 which extend through the inner spaces 63, 73 into the top of the
tank 10. Since the capacities of the tanks 60, 70 are virtually
unlimited and since the fluid consumption of the wrapper filament
spinnerets 12, 16 is very small compared to that of the core
filaments spinneret 11, the apparatus may be operated for a
virtually indefinite period without needing to refill the rotating
tanks 60, 70.
In many cases it is preferable to provide a wrapper filament of the
same filament type and denier per filament as the core filaments.
However, for other uses, it is not essential to meet this
requirement, and using any of the forms of apparatus heretofore
described in this specification the wrapper filaments may indeed be
composed of other types of filament, and of deniers which differ
from the deniers of the core filaments by suitably selecting the
chemical composition, shape, etc. of each filament. For example, it
is possible to use wrapper filaments which may be of different
chemical nature, or of different cross-section from the core
filaments or from each other. Indeed, the wrapper filaments may
even be of a type that may later be dissolved for the purpose of
removing them from the core filaments after the fabric has been
formed.
Although this invention may be utilized in conjunction with core
filaments which have been drawn, (as by applying the packages 32
and 34 at the location 32', 34' in FIG. 1) or even with wrapper
filaments which have been drawn, it is preferred for reasons of
strength that the very fine wrapper filaments be aplied in the
undrawn state. It is also highly preferred that both the core
filaments and the wrapper filaments be undrawn at the time the yarn
is assembled, and that they subsequently be drawn concurrently. In
come cases, straggler filaments are a problem, especially when the
wrapper filaments are loosely wrapped, and drawing eliminates all
stragglers.
The use of undrawn filaments is particularly advantageous with
respect to dyeing, because they can be dyed more deeply and with
radically better penetration when they are undrawn.
When undrawn filaments are used, it is usually necessary to apply a
steeper initial helix angle .theta. than is the case with drawn
yarns. This is because the drawing tends to decrease the helix
angle, making the helix angle shallower. Undrawn yarn packages cost
less than drawn yarn packages, and are much less susceptible to
breakage, particularly when filaments are plied.
In using the apparatus of FIG. 3, wherein the filament packages are
positively driven, it has been observed that the peripheral speed
of the filaments varies depending upon the diameter of the filament
package at the time. Thus, with constant speed drive, the
peripheral speed of the filaments decreases as the filaments are
removed from the package. It is preferable to compensate for this
effect by gradually increasing the speed of rotation of the
filament package as its diameter decreases and this can be
accomplished by using standard electronic devices well known in the
textile field, for maintaining a constant peripheral speed of the
filaments.
A wide variety of other modifications may be made. For example,
when it is desired to produce a crimped continuous filament yarn
which is nevertheless sufficiently compact to be processed
mechanically without twisting or other treatment, the core
filaments may be crimped in the undrawn condition and then
subjected to counterclockwise and clockwise helical wrapping of
wrapper filaments, following which the product may be drawn. The
drawing tends to remove a substantial amount of the crimp, but
subsequent heat setting restores some of the crimp and produces a
yarn having beneficial characteristics.
On the other hand, it is sometimes desirable to dye the undrawn
core filaments, with or without crimping, and then to perform the
clockwise and counter-clockwise helical wrapping operations,
followed by drawing and heat setting. This is advantageous because
of the dye receptivity which is inherent in undrawn filaments.
In accordance with this invention, yarns can be made which are
self-texturizing by using as the wrapper filaments materials having
different shrinkage characteristics than the material of which the
core filaments are composed. The use of wrapper filaments which
shrink more than the core filaments also tends to produce a yarn
having pronounced qualities of coherence and compactness.
Yarn in accordance with this invention may, of course be subjected
to one or more subsequent operations, such as twisting or jet
entangling, for example. Indeed, in some types of ordinary jet
entangled zero twist yarns, subsequent handling operations tend to
take out a significant amount of entanglement. With yarn according
to this invention, the presence of the helically arranged wrapper
filaments tends to provide a permanent base, or anchor, for
filaments subsequently displaced by jet entanglement and the
product is thus more resistant to disentanglement during subsequent
processing or handling operations.
Various other modifications may be resorted to without departing
from the spirit and scope of this invention. For example,
equivalent elements may be substituted for those specifically
disclosed herein, certain features of the invention may be used
independently of other features, and various modifications may be
made in the form of the method by which the wrapper filaments are
applied to the core filaments, all within the spirit and scope of
this invention as defined in the appended claims.
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