Method of manufacturing a composite yarn having a spandex core and a texturized thermoplastic covering

A method of manufacturing a composite yarn and composite yarn produced thereby in which a spandex yarn is fed to an air entangling or covering jet while being pre-elongated. Simultaneously, a multifilament partially oriented thermoplastic yarn is fed to the yarn entangling or covering jet while being partially or completely drawn to orient further or completely the thermoplastic yarn. The thermoplastic and spandex yarns are fed through the yarn jet while the filaments of the thermoplastic yarn are entangled to produce a composite yarn with the spandex yarn as the core and the thermoplastic yarn as a covering therefor. The composite yarn is then fed through a false twister and false twisted with the false twist being heat set in the thermoplastic yarn at a temperature which does not adversely affect the spandex core to produce an air entangled false twist texturized composite yarn. If not completely oriented when false twisted, the thermoplastic yarn is further drawn to complete its orientation while being false twisted.

FIELD OF THE INVENTION 
This invention relates to textile yarns and more particularly to composite 
textile yarns having an elastic core and a covering of non-elastic 
filaments. 
BACKGROUND OF THE INVENTION 
Textile yarns having elastic properties are widely used in various textile 
applications. Spandex yarns are most prevalently used to provide the 
elastic properties in such textile yarns. Because of the surface 
characteristics of spandex, however, bare or uncovered spandex yarns have 
only limited application. 
Typically, the spandex is incorporated with other textile fibers or 
filaments in composite yarns, with the other textile fibers or filaments 
forming a covering or sheath around the spandex which defines a core 
within the covering or sheath. Such composite yarns have been heretofore 
produced by wrapping one or more yarns of the other textile fibers or 
filaments around the spandex core by passing the spandex core 
longitudinally and axially through a wrapping spindle during which the 
covering yarn(s) is wrapped around the core. The density of the covering 
or sheath may be strictly controlled by the number of wraps per inch of 
the covering yarn(s) about the spandex core. 
While such wrapped, composite yarns have numerous advantages, they also 
have disadvantages and deficiencies. Such disadvantages and deficiencies 
include a relatively slow production rate and a relatively limited length 
of composite yarn produced. 
Because of the limitations, disadvantages and deficiencies of such wrapped 
composite yarns, attempts have been made to provide alternative ways of 
producing composite yarns, particularly where the covering or sheath is 
formed of a multifilament thermoplastic yarn. Such attempts have included 
the entangling of the filaments of a thermoplastic covering yarn with the 
spandex core by passing both yarns together through an air jet or similar 
fluid entangling device. Other attempts have included passing the 
thermoplastic covering yarn and the spandex core together through a 
friction false twister. 
These previously proposed attempts have provided increased rates of 
production and increased lengths of composite yarns produced. However, the 
composite yarns produced have exhibited erratic and insufficient coverage 
and other less than desirable surface characteristics. Additionally, the 
air entangled composite yarns have typically employed only fully oriented 
or fully drawn covering yarns. 
With the foregoing in mind, it is an object of the present invention to 
provide a composite elastic yarn and method of manufacturing the same 
which overcomes the aforementioned limitations, disadvantages and 
deficiencies of prior composite elastic yarns and methods of manufacture 
thereof. 
SUMMARY OF THE INVENTION 
The foregoing object of the invention is accomplished by a method of 
manufacturing a composite yarn and by the composite yarn produced thereby 
in which a spandex yarn is fed to an air entangling jet. A multifilament, 
partially oriented, thermoplastic yarn is also fed to the air entangling 
jet. The spandex and thermoplastic yarns are fed through the air jet 
wherein the filaments of the thermoplastic yarn are entangled with each 
other and with the spandex yarn to produce a composite yarn with the 
spandex yarn as the core and the thermoplastic yarn as a covering 
therefor. The thusly produced composite yarn is then fed through a false 
twister wherein the composite yarn is false twisted and heated to a 
temperature to set the twist in the thermoplastic yarn, but below a 
temperature to affect adversely the spandex core to produce an air 
entangled, false twist texturized composite yarn. The thermoplastic yarn 
is drawn to complete its orientation in feeding the same to the air jet, 
or in feeding the same through the false twister or partially in feeding 
the same to the air jet and partially in feeding the same through the 
false twister. 
In the drawings and specifications, there have been set forth a preferred 
embodiment of the invention, and although specific terms are employed, 
they are used in a generic and descriptive sense only and not for purpose 
of limitation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now more particularly to the drawings and specifically to FIG. 1, 
an air jet entangling or covering apparatus generally indicated at 10 is 
schematically illustrated. A multifilament, partially oriented, 
thermoplastic covering yarn 11 is supplied from a package 12 supported for 
unwinding rotation in a manner not shown. Thermoplastic covering yarn 11 
will be selected depending upon the characteristics desired in the 
finished yarn. Probably most frequently, the covering yarn 11 will 
preferably be nylon 6.6. Covering yarn 11 is fed from package 12 partially 
around a first guide 13, a second guide 14, and a third guide 15 to a pair 
of first draw rolls 16 and 17 by way of a fourth guide be. Covering yarn 
11 is wrapped from 5 to 7 times around the draw rolls 16 and 17. 
A spandex core yarn 20 is supplied by a package 21 supported by a pair of 
supply rolls 22. Spandex core yarn 20 may be monofilament or multifilament 
depending upon the characteristics desired in the finished yarn. Spandex 
core yarn 20 passes partially around the guides 15 and 18 to the first 
pair of draw rolls 16 and 17. As with covering yarn 11, spandex core yarn 
20 is wrapped from 5 to 7 times around draw rolls 16 and 17 in parallel 
convolutions to covering yarn 11. 
Supply rolls 22 are suitably driven in a manner not shown to supply core 
yarn 20 positively. Draw rolls 16 and 17 are driven in a manner not shown 
to provide a surface speed of draw rolls 16 and 17 relative to the surface 
speed of supply rolls 22 such that the spandex core yarn 20 is 
pre-elongated between supply rolls 22 and draw rolls 16 and 17. The amount 
of pre-elongation of core yarn 20 may vary, but typically will be from 
about 230% to 270%. 
From first draw rolls 16 and 17, covering yarn 11 and core yarn 20 are fed 
to a second pair of draw rolls 24 and 25 through an eyelet-type guide 26. 
Yarns 11 and 20 are again wrapped around second draw rolls 24 and 25 from 
5 to 7 times to ensure against slippage between the surfaces of draw rolls 
24, 25 and yarns 11 and 20. 
Preferably, first draw rolls 16, 17 and second draw rolls 24, 25 are 
rotated at relative surface speeds such that the partially oriented 
covering yarn 11 is further drawn between first draw rolls 16, 17 and 
second draw rolls 24, 25 to orient the covering yarn 11 a partial amount 
relative to that needed to orient completely the yarn 11. Still more 
preferably, the draw of yarn 11 between first draw rolls 16, 17 and second 
draw rolls 24, 25 is 50% or one-half of that needed to complete the 
orientation of yarn 11. The amount of draw needed to complete the 
orientation of partially oriented thermoplastic yarns varies from 
yarn-to-yarn. Typically, such further draw varies from about 15% to 30% 
depending on the type of yarn. 
Spandex core yarn 20 is further stretched or elongated between first draw 
rolls 16, 17 and second draw rolls 24, 25. The amount of such further 
elongation is equal to the amount of draw of covering yarn 11. Compared to 
the amount of pre-elongation between supply rolls 22 and first draw rolls 
16, 17, this further elongation of core yarn 20 is quite small. 
Second draw rolls 24, 25 feed covering yarn 11 and core yarn 20 to an air 
jet 27 over a first air jet guide 28 in parallel, contiguous relation. 
Covering yarn 11 and core yarn 20 pass through the air jet 27 where the 
filaments of the covering yarn 11 are air entangled with core yarn 20. Due 
to the greater tension in core yarn 20 because of the pre-stretching or 
pre-elongation thereof, covering yarn 11 forms a covering or sheath around 
core yarn 20 in the air jet 27 to form a composite yarn 30. 
Composite yarn 30 exits the air jet 27 and passes over a second air jet 
guide 31. Composite yarn 30 then passes to a pair of delivery rolls 32, 
33, about which it is wrapped from 5 to 7 times. Delivery rolls 32, 33 are 
driven in a manner not shown to provide a surface speed thereof such that 
second draw rolls 24, 25 overfeed covering yarn 11 and core yarn 20 to air 
jet 27. The amount of such overfeed may vary, but typically it should be 
about 6% to 11%. 
Composite yarn 30 leaves delivery rolls 32, 33 by passing between such 
rolls and thence to a take-up means 34. Take-up means 34 winds composite 
yarn 30 into a yarn package 35. If desired, composite yarn 30 may proceed 
directly to further processing without being wound into the package 35. 
The air jet entangling or covering apparatus 10 just described is well 
known to persons skilled in the yarn throwing art. One such machine is 
manufactured and sold by D. Giudici and Figli of Italy. 
The composite yarn package 35 is next placed in the creel (not shown) of a 
false twisting apparatus, generally indicated at 40 and illustrated 
schematically in FIG. 2. Such false twist apparatus is well known to yarn 
throwsters and one such machine is manufactured and sold by D. Giudici and 
Figli of Italy. 
Composite yarn 30 is unwound from package 35 by a pair of feed rolls 41. 
Composite yarn 30 then passes through a heater 42. However, unlike 
conventional false twisting, composite yarn 30 does not contact heater 42, 
but is heated thereby solely by convection. From heater 42, composite yarn 
30 passes through a guide 43 and engages the peripheries of rotating discs 
44 of a conventional friction false twist means 45. Discs 44 of friction 
false twist means 45 impart false twist to composite yarn 30 which 
backs-up through guide 43 and heater 42 to the feed rolls 41. 
The false twisted composite yarn 30 is heated by heater 42 to a temperature 
sufficient to set the twist in thermoplastic covering yarn 11, but 
insufficient to affect adversely spandex core yarn 20. In conventional 
false twisting, it is common to heat thermoplastic yarns to temperatures 
of about 200.degree. C. to about 220.degree. C. when such yarns are nylon 
6.6. However, such high temperatures would adversely affect spandex core 
yarn 20. Accordingly, composite yarn 30 is preferably heated to a 
temperature of about 140.degree. C. to about 160.degree. C. 
After leaving discs 44 of friction false twister 45, composite yarn 30 
passes through the nip of a pair of draw rolls 46, 47. Draw rolls 46, 47 
are driven in a manner not shown to provide a surface speed relative to 
feed rolls 41 such that composite yarn 30 is elongated between feed rolls 
41 and draw rolls 46, 47 by an amount sufficient to draw further covering 
yarn 11 by an amount sufficient to complete the orientation of the 
partially oriented covering yarn 11. 
While it is preferred by this invention that the partially oriented 
covering yarn 11 have its orientation completed by being drawn partially 
in both the air entangling apparatus be and in the false twist apparatus 
40, it is contemplated by this invention that such partial orientation 
could be completed by having the covering yarn 11 fully drawn in either 
the air entangling apparatus be or in the false twist apparatus 40. The 
best finished yarn characteristics have been achieved when such 
orientation is completed by a draw of about 50% or one-half of the amount 
of draw needed to complete orientation of covering yarn 11 is accomplished 
in each of the air entangling apparatus 10 and the false twist apparatus 
40. 
From draw rolls 46, 47, composite yarn 30 is wound by a take-up means 48 
into a finished yarn package 50. Rolls 46, 47 are driven in a manner not 
shown such that the surface speed thereof is greater than the surface 
speed of take-up means 48 such that the composite yarn 30 is overfed by a 
predetermined amount onto package 50. 
In the drawings and specifications, there has been set forth a preferred 
embodiment of the invention, and although specific terms are employed, 
they are used in generic and descriptive sense only and not for purpose of 
limitation.