Filament yarn sizing
Why we need to size filament yarn?
The filament yarns have much more smoother surface and stronger as compare to staple yarn
then, why we need to size it? There is wide range of filament yarn from high twisted filament
yarn to low twisted multi-filament yarns. High twist filament yarns may not require sizing. But
if we do not size the low twist multi-filament yarn, they can create problems: if a single
filament breaks during weaving. It will make fuzz ball, float or skip that will ultimately cause
the loom to stop. It order to avoid these kinds of situations, we size the yarn.
The main function of size is to protect the yarn during looming process. That can only
happened if the size material possess good adhesion properties: there is a strong force of
att a tio etwee fi e a d size ate ial. These fo es a e usually Va De Waals’ o
Hydrogen Bonding. As we know that Hydrogen bonding is much stronger tha Va De Waals’
force so it implies that the size material that makes hydrogen bond will possess good adhesion
properties.
Some times when the size material do not have good adhesion properties we can add some
plasticizer to the size material to improve this properties. In addition to increase the adhesion
properties these plasticizer can also reduce the cost and have good film forming properties.
Figure 1 the configuration of filament yarn sizing machine.
Warp preparation
Warp preparation for filament yarn is same as staple yarn. Two basic technique are used.
a) Sectional warping
b) Direct warping/Beaming
Although the method is same but there are some steps and precautions which we have to
follow in the case of filament yarn warping.
Precautions sectional warping
Filament yarn can have luster and strain variations between and within the package so it is
important that we use cross creeling in order to avoid strips formation on beam. The other
major problem is rolling of end during warping. It can be reduced by using splitting rods and
condenser board. Otherwise these ends. Rolling can also be avoided by adding more number
of leases.
Precaution in direct warping
Direct warping is the much faster way to warp the yarn sheet. It has less problems and more
commercial. But to avoid stripiness we make different sets of back beams.
Sizing method
The sizing method of warp prepared from sectional warping and direct warping is different.
Because the in the case of section warping we have all the ends on a single beam but in the
case of direct warping total ends are equally divided on numbers of beams. The technique
use fo sizi g fo se tio al wa ped ya is alled Bea to Bea “izi g a d fo the othe it is
alled “lashi g .
The most important thing in beam to beam sizing is to maintain the proper stretch. Some
filament yarn can be overstretched during sizing process. Overstretched yarn become brittle
and cause yarn breakage during looming process. And after sizing it is important to use proper
splicing technique to insure that there is no stripiness and yarns are separated appropriately.
Similarly in slasher it is important to maintain the tension of each back beam and make sure
that they are tensioned equally otherwise stripiness will produce.
Factor influencing sizing
There are some which should kept in mind while sizing they can directly affect the quality of
the weavers beam. A list of these factor is given below.
a) Control of size bath: it is important to circulate the size material in the size box and
maintain the exact temperature of the size material to obtain the uniform sized warp.
b) Quetsch system: the pressure applied by the squeeze roller influence the amount of
size stored on the yarns. It is related to the composition of the quetsch roller.
c) Drying: drying of filament yarn is very critical process. It is mostly dome by steam
heated cylinder. These cylinders are coated with anti-sticking material to avoid
sticking. Drying temperature depends on the type of yarn.
d) Stretch: the over stretching of yarn can cause brittleness which will be problem in
looming. Over stretching can occur at three in sizing.
a. Betwee the wa pe s’ ea a d uets h olle
b. Between the quetsch roller and the first drying cylinder
c. Between the last drying cylinder and the draw roller.
e) Static electricity: static charge can be built up due to the friction between the yarn
sheet and drying cylinder. An electric static eliminator is used at the headstock to
overcome this problem.
Sizing material
Below is the list of properties that a size material (for filament yarn) must have:
a) Good adhesion properties
b) Less expensive
c) Should give appropriate amount of strength to the yarn
d)
e)
f)
g)
h)
Impart elasticity, flexing resistance, resilience and lubrication properties to the yarn
It should dry easily
It should not cause static charge build up on yarn
It should not be affected by the extreme humidity
It should be easily removable during desizing.
Reference
[1] P. Sabit Adanur, Hand Book of weaving, CRC press, 2001.
[2] J. S. SMITH, The Technology of Warp Sizing, Manchester & London: Columbine Press, 1994.