Method of making yarn

Method to produce an entangled yarn product by air entangling a drawn core yarn and a drawn effect yarn. The effect yarn draw ratio is higher than the core yarn draw ratio which results in a composite yarn in which the birefringence of the core yarn is greater than that of the effect yarn.

This invention relates generally to yarns produced by combining at least 
two yarns in an air jet to produce a continuous, multi-filament textured, 
spun-like yarn which will efficiently dye when made into a fabric. 
It is therefore an object of the invention to provide a novel method to 
produce a multi-filament yarn which will eliminate a speckled effect in a 
fabric produced therefrom when dyed a solid color.

Looking now to the drawing, there is shown one embodiment of an apparatus 
for producing the novel yarn composed of a core yarn and an effect yarn. 
In the preferred form of the invention, both the core yarn 10 and the 
effect yarn 12 are continuous, multi-filament, partially oriented 
synthetic yarns. 
The core and effect yarns 10 and 12 are combined in the air jet 14 to 
produce the textured yarn 16 which is delivered by the take-up nip rolls 
18 and 20 through the secondary heater 21 to the take-up roll 22. The core 
yarn 10 is delivered from the package 24 by the first delivery rolls 26 
and 28 to the second delivery rolls 30 and 32 to draw the core yarn 10 
after it passes over the pin heater 34 prior to delivery into the air jet 
14. 
The effect yarn 12 is delivered from the package 37 to the first delivery 
rolls 38 and 40 and is drawn by the second delivery rolls 42 and 44 after 
it passes over the pin heater 46. From the delivery rolls 42 and 44, the 
effect yarn 12 is delivered to the air jet 14. 
In the preferred form of the invention two sets of nip rolls 50, 52 and 54, 
56 are employed to provide a stabilizing zone therebetween prior to the 
supplying of the composite yarn to the take-up 22. 
The speeds of the delivery rolls are pre-selected to provide a desired 
result in the yarn produced. In the preferred form of the invention, the 
speed of the rolls 26, 28, 38 and 40 is so selected that the speed of the 
effect yarn 12 being delivered thereby is less than the speed of the core 
yarn 10. The speeds of the delivery rolls 30, 32, 42 and 44 are so 
selected that the delivery speed of the effect yarn 12 is greater than the 
speed of the core yarn 10. In the preferred form of the invention, since 
partially oriented yarn is being run, the speeds of rolls 30, 32, 42 and 
44 are so selected to draw the effect and core yarns. The speed of the 
delivery rolls 18 and 20 is so selected that the yarn 16 delivered 
therefrom is at a speed lower than the speed of either the core yarn 10 or 
the effect yarn 12, respectively, from the rolls 30 and 32 or 42 and 44, 
but greater than the speed of the yarn delivered by the rolls 38 and 40 or 
26 and 28. 
In operation the higher speed, overfed effect yarn 12 forms crunodal loops 
in the air jet 14 which project through and intermingle with the core yarn 
10 and are twisted to hold the filaments of the composite yarn together to 
provide a spun-like yarn. It has been found that the best effort is 
achieved when the air pressure supplied to the jet is 100 psig or greater. 
"P" should be equal to or greater than 100 psig when the yarn denier is 
300 or less. 
An exceptionally attractive spun-like yarn is achieved when the draw ratios 
of the core and effect yarn are different. This is accentuated when the 
draw ratio of the lower speed core yarn is less than the draw ratio of the 
higher speed effect yarn. Preferably the core yarn draw ratio is 
approximately 10% greater than the draw ratio for the effect yarn. It has 
been found that yarn produced in accordance with this difference in draw 
ratio eliminates the "measle" or speckled effect produced when dyeing 
fabric woven or knitted from yarn made without this draw ratio 
differential. 
It has been found that the core yarn birefringence is greater than the 
effect yarn birefringence when the core yarn draw ratio is less than the 
effect yarn draw ratio. For the sake of this description, birefringence is 
defined as the difference in refractive index for light polarized 
perpendicular to the fiber axis and for light polarized parallel to fiber 
axis. 
The air jet 14 is a commercially available type and does not, per se, form 
a part of the invention other than it accomplishes the desired result of 
entangling and texturing the yarn. 
The following is an example of the production of a yarn in the manner 
hereinbefore described. 
EXAMPLE 
The effect and core yarns are 255 denier, 68 filament, DuPont 56T partially 
oriented polyester yarns. The resultant combined yarn is 330 denier 
polyester yarn. 
The combined yarn is formed under the following parameters: 
Effect yarn velocity from first delivery rolls--256 meters/minute 
Core yarn velocity from first delivery rolls--263 meters/minute 
Pin heater 34 temperature--135.degree. C. 
Effect yarn velocity from second delivery rolls--472 meters/minute 
Core yarn velocity from second delivery rolls--434 meters/minute 
Draw ratio effect yarn--1.844 
Draw ratio core yarn--1.65 
Jet air pressure--140 psig 
Pin heater 46 temperature--135.degree. C. 
Yarn velocity from jet to rolls 50, 52--406 meters/minute 
Yarn velocity from stabilizing zone--412 meters/minute 
Combined yarn velocity to take-up rolls--408 meters/minute 
Secondary heater 21--off 
Combined yarn take-up velocity--400 meters/minute 
It is obvious that an air textured spun-like yarn has been provided by 
efficiently combining a drawn core yarn of high birefringence and a drawn 
effect yarn with a lower birefringence in an apparatus which employs air 
under pressure to commingle and texture the filaments of the core and 
effect yarns and which operate at an increased efficiency to produce a 
better yarn product. The yarn produced by the disclosed method when made 
into fabric does not have a "measle" or speckled appearance when dyed in 
solid colors. It has been found that having the draw ratio of the core 
yarn less than the draw ratio of the effect yarn provides the desired dye 
effect in solid color fabrics. 
Although the preferred embodiment of the invention has been described 
specifically, it is contemplated that many changes may be made without 
departing from the scope or spirit of the invention, and we desire to be 
limited only by the claims.