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Essentially the spinning process

High-speed spinning (lon

Low-speed spinning (sho

Table 3 shows briefly the mainlow-speed spinning process is afiber, while for the production of

either the fast or slow spinning p

Fiber an

A brief description is given hererespectively for conversion of thfilament and spun bonded

Fiber spinning

can be divided into two classes

g)

rt)

ifferences between the two types of process.opted for the production of cotton and wool sy

continuous filament (CF) or bulk continuous fila

rocess can be used.

Non Woven Processing technologies

nder of the basic steps of the three processesgranule into staple yarn, continuous filament,

ormally, thestem staplement (BCF)

usedbulk continuous

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PP

The production technology for c21. It includes:

Extrusion- The extruder is of thto 30 and compression ratio = 1:Metering - One or more gearedto the spinning pack. Their purpconstant way to prevent fluctuati

Spinning- The spinning pack is1) filter2) distributor, which distributes t3) die. The die hole diameter vathe length/diameter ratio varies ffar as the absence of dangerousfigure 22

.

Staple yarn process technology

tton and wool staple yarns is schematically re

e type commonly used for polypropylene, with3.5.spinning pumps receive the molten polymer anse is to homogenize the product, feeding the s

ons due to the screw.

comprised of three parts:

e molten polymer uniformly over the die surfaies from 0.5 to 1.5 mm, according to the denier

rom 5 to 20. Experience shows that the best d rheological phenomena is concerned, is the o

resented in fig.

/Dratio equal

d send it throughpinning pack in a

es required, and-hole profile, ase shown in

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Quenching- This is generally made up of a column whose purpose is to convey the cooling airfor the yarn (extrudate), without causing its damage (bulging, sticking). It is composed of twoparts:1) blower box or air distributor (fig. 23), which should be designed in such a way as not todistribute the air onto the extrudate in a violent way. Generally, a good box will distribute3m3/minute of air without giving rise to damage

2) air conveyer pipe. This is situated immediately after the blower box and collects the air fromthe latter together with the extrudate of the die. Its length must be such as to allow a completecooling.Finish- The finishing operation, that is immersion of the fiber in a concentrated antistatic, slip,cohesion etc. solution becomes necessary in order to impart to the fibers the propertiesindispensable to their processing on the textile machines.Hot stretching- The stretching operation is essential for conferring precise physico-mechanicalproperties. The stretching operation takes place between two groups of rolls rotating at differentspeeds. Between the two rolls there is a heating element (oven, plate, etc.) which confers thethermal energy required to overcome the AE due to the passing of the molecules to a higherstate of potential energy (oriented state).Crimping- This is a thermal-mechanical treatment that imparts to the fiber a characteristic

undulationhighly important parameters, which give respectively the number of undulations andtheir intensity.

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Thermosetting- Thermosettingstresses and relaxes the fiber. BCutting- Accordingly as to whetis adjusted at a minimum of 20Packaging- Normally, the cut sshipment.

b. CF PP = Continuous filame

The first six steps (extrusion, mesame as for staple yarn, but theThe hot stretching operation canUsually, batch stretching is neceThe packaging step always con

is a treatment in hot air or steam, which removy this the fiber is heat stabilized and its denier iher the system is cotton type or wool type, them to a maximum of 120 mm.aple is pressed in or in smaller sized ballots, re

t process technology(fig. 24)

tering, spinning, quenching, finish and hot stretcrimping, thermosetting and cutting operationsbe done in continuous with the previous step ossary when spinning speeds are very high.ists of winding the stretched yarn onto reels or

es internalincreased.

length of the cut

ady for

ching) are theare left out.r batchwise.

cops.

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c. BCF PP = Bulk continuous filament process technology (fig. 25)

The first six steps are the same as for CF. After stretching, and prior to being wound onto reels,the filament is subjected to a bulking operation by means of steam.

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d. PP Spun bonded process t

In the first four steps, the procesquenching, the filament is stretc300 to 500 times higher than its

The bundle of filaments is thena continuous belt prior to the bo

mechanical chemical thermal

In this way, non-woven fabrics awhen compared with the non-woundulated by combs, the cohesior with those obtained through tvehicle: procedure of the paper-

chnology (fig. 26)

s is similar to the three processes previously died and pulled towards the nap forming system

extrusion speed.

ispersed by various procedures and collected iding operation, which can be:

re produced, which possess the best mechanicven fabrics obtained through the dry route (sn of which is imparted through the mechanical

e wet route (nap formation with short fibers iill type)

cussed. Afterat a speed from

n layer form onto

al propertiesort fiberschemical route),an aqueous

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Polypropylene MF grades for

Tables 4 and 5 give the typical g

pinning processes

rades marketed on for various processes and pplications.