Chapter 4
5.1 The idea of enhancing cotton
Gives advantages in finer counts which are produced from specific grades of cotton ( Pima).
Yarn Tenacity (Strength and Softness) increases as Modal blending ratio increases.
It improves the processing performance of cotton.
It improves the consistency and quality of cotton yarns.
Overall spinning performance is enhanced by blending Modal with cotton.
This creates a new group of fabrics with new aesthetic properties and functionality compared to cotton fabrics
5.2 Lenzing Modal Card
... Produced from beech wood
... The Lenzing Modal production process is environmentally-friendly due to the exceptionally high recovery rate
... Low utilization of land and water during production – cotton requires up to 100 times more water than Lenzing Modal
... Lenzing Modal makes everything soft and coz
... Perfect for blends with cotton: mercerizability, alkali resistance, tone-in-tone dyeing
... Can be blended with all other fibers without any difficulty
... Lenzing Modal is a globally protected trademark
... Lenzing is the Modal specialist and has produced the fiber for fifty years
... Lenzing Modal is used by leading brand collections With special technical & commercial support from Lenzing fibers of Austria, Modal is tried and used in 5 to 50% blend with cotton for fine yarn counts ( 200s, 30s, 40s Ne )and this not only gives increase in yarn strength (CSP) but also reduces imperfections with smooth and shine on yarn. Overall quality and life of
Fibre Properties
Chapter 5
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end product made is much better, no combing process is required, productivity is increased_ With continuous increase in demand of supima, DCH, giza and other ELS cottons, using this special viscose fiber not only saves cost but also gives very good and consistent yarn quality. Good quality and high end cotton prices will be continuously increasing in coming years and availability will reduce. This is already observed in supima where prices are doubled in last one year. Use of Modal fiber gives us various benefits, since this is manmade cellulosic fiber only and one kind of viscose only, it has to considered like viscose with no import duties.
5.3 Modal fibre Characteristics:
o Soft, strong, absorbent
o Fibrillated during wet processing to produce special textures
o Excellent wet strength
o Wrinkle resistant
o Very versatile fabric dyable to vibrant colors, with a variety ofeffects and textures.
o Can be hand washable
o Simulates silky, suede, or leather touch
o Good drapability
o Biodegradable.
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ROCESSING GUIDELINE
SPINNING OF LENZING MODAL AND COTTON ACCORDING TO
THE THREE-CYLINDER AND OE-ROTOR SPINNING PROCESS
Recommendations for processing short staple MODAL fiber
The cellulose textile fibers Lenzing Modal are available in different types of machines, which are generally suitable for the processing of man-made fibers.
Procedure
Chapter 6
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The following processing recommendations and machine setting data apply equally to Lenzing Modal. They are based on our total experience to date and are valid for the processing techniques and machine types in general use at present.
6.1 Flock material and air conditioning
Lenzing Modal fibers are treated with a special spin finish which includes an antistatic agent to ensure good spinning properties. There is no need for any further additives in the spinning process.
However, if these fibers are subsequently dyed, a suitable secondary finish must be applied, because the flock loses the original preparation during the dyeing process.
Trouble-free running properties can be expected if the room air conditioning is within the following limits:
Room temperature: 24 – 26 degrees Celsius
Relative humidity: 50 – 60 %
As is the case all man-made fibers, it is advisable to allow the unpacked and opened bales time to acclimatize before processing. This should be a longer period in the cold winter months.
6.2 Bale laydown
MODAL bales weigh approximately 350 kg each and should be used, where possible, sequentially according to lot number and fiber production date. As with all man made fibers, adequate stock rotation of fiber, material in process and yarn should be carried out in order to optimize process continuity, avoid the build up of old stock and in order to minimize the risk of longer term process variations due to excessive storage intervals between materials in use.
Whilst MODAL fiber has significantly less bale to bale variation than cotton, as with other man made fibers, as many bales as possible should be used in each laydown. This will ensure that fibers are thoroughly blended. Where continuous use of MODAL fiber is anticipated, programmed use of bales from a range of deliveries is recommended. It is normally recommended to use a minimum of 15 bales in each laydown.
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Figure 1
6.3 Batch Spinning
This technique is based on the assumption that the customer is using only a limited quantity of fibers which he blends together, but which are spun as a separate entity. Where are large number of bales are involved, it is advisable to use the continuous spinning technique described overleaf.
6.4 Continuous Spinning
This technique is understood to mean the continuous and uninterrupted spinning of material supplied at different times over a prolonged period. In order to ensure uniformity of shade, the overlapping processing of three to four deliveries is necessary.
Furthermore it is recommended to work with a laydown consisting of minimum 10 to 12 bales (better are 20 to 24 bales). The fiber quantities taken from different bales should be comparable in weight.
Figure 2 illustrates the diagonal processing of a stock of 12 bales from a number of consecutive deliveries.
6.5 Blending and Opening Machines
For the opening-up of Cotton and Lenzing Modal fibers the opener combinations normally used in today’s fiber processing industry will be found suitable. In the main, these combinations comprise a bale opener or a mixer bale opener and an on-line opening machine. The opener subsequently takes over the role of feeding the cards. The following points should be borne in mind in connexion with the achieving of a good degree of opening:
a) The beater speed of the Kirschner cylinder should be set at between 600 and 800 rpm.
b) The distance between the beating area and the mould or the draw-in roller should be set at between 8 and 11 mm.
6.6 Carding
The processing of Cotton and Lenzing Modal is usually on modern, flock fed units. In order to ensure efficient fiber opening, it is extremely important that the cards are highly ground and in a good condition, and further that they have been set in accordance with the manufacturers’ instructions. It has also been found to bee of
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Figure 3
advantage when processing these fibers, if the lickerin has a wire with a negative top rake of 5 – 10 degrees.
When processing only Lenzing Modal we recommend the following card clothings, settings and speeds:
1.) Card clothings
Licker-in 32 to 40 points / inch² / 5° positive
Main cylinder 600 to 720 points / inch² - 15° to 25°
Flats 300 to 420 points / inch² - flexible wire
Doffer about 360 points / inch² 30°
Fix flats under licker-in 90 p. / inch²
Fix flats above licker-in 90 and 160 p. / inch² or 160 and 240 p. /
inch²
Fix flats above doffer 550 to 600 p. / inch²
2.) Card settings (1/1000")
Feed table / licker-in 28
Licker-in / knife 18
Licker-in / fix flats under licker-in 18
Licker-in / main cylinder 8
Fix flats above licker-in / main cylinder 28 to 20 declining
Flats / main cylinder 12/12/10/10/9
Fix flats above doffer / main cylinder 10
Main cylinder / doffer 4
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Gap between both squeeze rolls 12
Total draft 80 to 120
3.) Rpm, sliver count and others
Licker-in (rpm) 800 to 1000
Main cylinder (rpm) 350 to 400
Sliver count Ne 0,10 to 0,13
Flat speed (mm / min) 80 to 140
Production rate (kg/h) 25 to 60 (Depends on the yarn spinning technology, yarn quality and on the type of card)
6.7 Drawing
When processing either Lenzing Modal fibers alone, two passes on the drawing rollers will generally be found sufficient. Basically, all conventional-type draw frame systems should be found suitable – provided they can be adjusted to the length of the staple. The doubling can be selected 6 or 8 times, and also the total drafting. Generally speaking, it will be found that cylinder loading commonly used for man-made fibers are also sufficient for Cotton and Lenzing Modal fibers.
The weight applied to the drawing frame – depending on the cylinder loading – should be so selected that the clamping of the slivers to be drawn is always sufficient to give fiber control.
Most of the synthetic material covers on the market today ( 80° - 84° Shore Hardness) will be found suitable for the pressure cylinders. A precondition for trouble-free running properties is the room temperature and the good condition of the cylinder covers, which should not show any signs
of damage or contamination. Roller lapping – which can occur at very high processing speeds, and where the air conditioning is not optimal, may make it necessary to lacquer the rubber roller with a suitable cylinder lacquer.
In fig. 4 you can see the appropriate settings for different drawing systems.
Figure 4
6.8 Speed Frame
For the processing of Cotton and Lenzing Modal, high load drawing rollers such as three cylinder double apron drawing equipment are used.
As far as rubber rollers for the cylinders are concerned, the same remarks apply as under >>Drawing<<.
The sliver count should be between 0,20 and 0,30 Nm. The total draft should be between 6 and 12. The break draft serves to align the slivers in the pre-drafting
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