Spandex (Part 2)
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Transcript of Spandex (Part 2)
8/11/2019 Spandex (Part 2)
http://slidepdf.com/reader/full/spandex-part-2 1/12
Manufacturing
End uses
Riaz-ul-haq
060820-054
Manufacturing steps
Polymer manufacturing (polyurethane).
Spinning.
Finishing & Drawing.
Winding.
8/11/2019 Spandex (Part 2)
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Polyurethane manufacturing:
The manufacturing of a polyurethanerequires a pre-polymer.
Pre-polymer production:
In this process a pre-polymer is obtainedthrough high-molecular-weight diol.
In this mixing of highly purified ingredientsat high temperatures takes place.
In this process the softsegments(polyesters or polyethers) areproduced.
Pre-polymer production continue..
mixing of three moles of a polyglycol with
two moles of a diisocyanate so that a low-
molecular-weight polymer having hydroxyl
groups is obtained.
Then one mole of this product is reacted
with two moles of another diisocyanate the
hydroxyl end groups are replaced by
isocyanate end groups which is medium-
weight polymer (second pre-polymer) .
This viscous syrup is called a pre-polymer.
8/11/2019 Spandex (Part 2)
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Segmented polyurethane production:
In this process the conversion of pre-
polymer to polyurethane (high-molecular-
weight) take place.
the reaction take place when pre-polymer
is combined with diamine or some other
bi-functional active hydrogen compound
such as a diol
Segmented polyurethane continue..
The polymer produced has the following
structure:
-ABABABA-A-A-A-
ABABABABA-A-A-A-ABABABA-
Where A is diisocyanate and B is diamine.
8/11/2019 Spandex (Part 2)
http://slidepdf.com/reader/full/spandex-part-2 4/12
Spinning:
There are three major types of spinning:
Dry spinning
Wet spinning
Melt spinning
Dry spinning:
In dry spinning the
heated polymer
solution is forced to
pass through the
spinneret into a hot
gaseous region in a
spinning tube andthe solvent is
removed.
8/11/2019 Spandex (Part 2)
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Wet spinning:
There are two methods to perform wet -
spinning.
In the first method, The polymer solution
is extruded into the coagulation bath by
means of orifices in the spinneret.
After coagulation the fiber is wound aboutdue to combining and fusion of the
filaments.
8/11/2019 Spandex (Part 2)
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Wet spinning continues…
In second method
the pre-polymer is
used.
In this method the
pre-polymer solution
is extruded into a
liquid bath to form
diamine solution andthe chain
enlongation take
place.
8/11/2019 Spandex (Part 2)
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Melt spinning:
This technique is not in practice commercially.
In this technique the spandex fiber is produced at hightemperature by simple extrusion of the polymer solutionand polymer is kept for a very short time at hightemperature for cross-linkage.
The excess cross-linking and the formation of gel takeplace if the polymer is Kept for more than a short whileat high temperature. That is why this process is not usedcommercially in the production of spandex fibers.
Finishing & Drawing: To remove the stains different fiber finishes are
used.
Commercially complex mixtures are used theyalso provide proper lubrication charge protectionand make the fiber non-interferer to subsequentdyes.
Most types of spandex fibers are drawn orstretched and heat-set when they are in the
enlongation state to yield a finer yarn size, high-modulus, low stretch and lower set.
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Winding:
It is the final process in the manufacturing
of spandex fibers. It is winding onto tubes
,spools or cones. The process is carried
out on
Conventional textile epuipment.Extra care
is required during the process when it is in
the low or uniform tension.
End-Uses:
Generally there are six end-uses of spandex fiber:
Circular knits:
They include active wear, swim wear,casual wear e.t.c
Hosiery:
Socks, briefs e.t.c
Non-woven:
Personal care products like diapers.
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End-uses continues…
Narrow fabrics:
Waistbands, straps, belts
e.t.c.
Warp knits:
Body shaping garments.
Stretch woven:
Stretch cloths like skintight jeans, stretch bandages and wraps.
“There are also several uses of
spandex fiber.Radici spandex
type S-17 is used to avoid ultra
violet rays,suntan oil and
perspiration.It is also chlorine
resistant.Elastoester is used for
outerwears and
furnishing.Heavier sizes,like 1120
den and above, are used in the
elastic webbings and straps
End uses continues……