Man made fiber spinning

• Spinneret: A nozzle or plate provided with fire holes or slits through a fibre forming solution or melt is extruded in fibre manufacturing is called spinneret.. Features of Spinneret:

Man Made Fiber Spinning

Prepared By : Mazadul Hasan sheshir ID: 2010000400008

13 th Batch (session 2009-2013) Department : Wet Processing Technology Email: mazadulhasan@yahoo.com

Blog : www Textilelab.blogspot.com (visit)

Calssificatoin of fibres

MMF are produced in three types –

1 Filament:Filament fibres are spun from

spinnerets with 350 holes or less is determined

by the size of the yarn to be made

Monofilament: This filament is made only of a

single filament.

Multifilament: These filaments are made of more

than one filament.

2 Staple:Staple fibre is of limited and relatively

short length

3 Filament tow An assemble of twist free fibre.

•Molecular weight should be high.

•Crystallinity – high not suitable.

•Resistance to different chemical.

•Orientation – Physical and chemical symmetry.

•Straight chain structure.

•Glass Transition Temperature (Tg) – Should be near to Room Temp.

•Crystalline Melting Point (Tm) - 200o – 300o c is suitable.

•Polymer should be soluble in some solvent from which it can be spun.

•Hygroscopic nature – Should be hydrophobic

Synthetic Spinning System

• Spinneret: A nozzle or plate provided with fire holes

or slits through a fibre forming solution or melt is

extruded in fibre manufacturing is called spinneret This is the most important part of a MMF producing m/c The number of holes, sizes and shapes vary

with the filament desired.

Features of Spinneret:

Spinneret length:10-25 mm Spinneret diameter: 30-200 mm Spinneret thickness: 3.0 mm Hole dia: 0.1.-0.8 mm

Problems:

-Breaking (On account of high pressure and temp)

Clogging (The holes can be blocked for solid particles

mix with polymer solution).

Remedies:

- For breaking problem: the spinneret is to be changed.

-For clogging: the spinneret should be cleaned after some days.

Number of holes in spinneret:

1 For monofilament: 1-3

2 For multifilament: 100-1000

3 Filament tow:up to 50,000

Flow chart of MMF production:

1 Manufacture of the fibre forming polymer.

2 Spinning ( extrusion through spinneret)

3 Stretching/Drawing ( improving strength and crystallinity)

4 Texturing/Crimping ( developing natural fibre properties)

5 Intermingling/Interlacing( applied instead of twisting)

6 Heat setting( made dimensionally stable)

7 Cutting: According to requirements.

1 Manufacturing of the fibre forming polymer:

• All man made fibres are composed of long

chain molecules known as polymer which are formed by chemical processing

• Common groups in polymers –

– Amide or Peptide groups ( -CO-NH-)

Spinning:

• The conversion of polymer into fibre is called spinning The fibre forming substance is made temporarily fluid, extruded through spinneret and then returned to solid state (by

solidification) in fibre form.

• Three types of spinning process:

– Melt spinning (Synthetic).

– Wet spinning.

– Dry spinning.

SPINNING of polymers

Wet

that can be evaporated

and must be removed by chemical means

Wet spinning

In wet spinning the solution of fibre-forming material is extruded into a coagulating bath that causes the jets to harden as a result of chemical or physical change

Viscose, for example, is wet spun The solution of cellulose xanthate is extruded into an aqueous solution of acids and salts, in which the cellulose is regenerated to form solid filaments

Man Made Fiber Spinning Technology

02 Spinning: Melt spinning:

• The process of spinning by which fibre or

filament is produced from melted polymer chips

by extruding through spinneret continuous

filament produced here.

• Number of filament depends on number of

holes in spinneret

• It is the most critical operation in the production

of nylon polyester, and polyolefin, poly

propylene fibres as number of fibre properties such as uniformity, crystallinity, and orientation are imparted to the yarn during processing.

02 Spinning: Melt spinning:

02 Spinning: Melt spinning:

– Non toxicity and no risk of explosion.

– High production speed (2500 – 3000 ft/min)

– Low investment cost.

• Disadvantage:

– Required more proper maintenance of the m/c

– Heat of input is high.

02 Spinning: Melt spinning:

Typical melt spinning:

Polymer Melting point

• In dry spg n , the fibre forming polymer dissolved

in a volatile solvent is introduced into a heated drying chamber where the solvent is

evaporated and solid fibre is obtained through spinneret

• This process is used for Acetate and some

polyacrylonitrile fibre.

• Dry spinning solvent:

I) Cellulose -Acetone + (2-6) % water

II) II) Triacetate -Methylene chloride (40%)

+ Methanol (10%) III) Poly acrylonitrile -Di-methyl formamide or

Dimethyl acetamide.

IV) Spandex - DMF, DMAC.

V) Modacrylic - Acetone.

Dry spinning Process

Dry spinning Process

• Advantage:

– Suitable for producing fine denier fibres – No need of wash of fibre.

• Disadvantage:

– Investment cost is high.

– Toxic and risk of explosion.

– Heat input is very high.

– Can not be used for staple fibre production.

• Properties of solvent:

– Solvent should not be volatile.

– It should be organic.

– It should have low boiling point.

– It should be comparatively cheap.

– It should be thermally stabilized.

– It should be non toxic.

• In wet spinning a suitable solvent is used to prepare fibre forming solution and another coagulant is used

in coagulating bath

• Solution is extruded through spinneret and in contact

of coagulant cellulose is regenerated.

Fibre Solvent Coagulant

Viscose Alkaline water Dill H2SO4 + Na2SO4 +ZnSO4

PVA Water Aqueous NaOH

PAN DMF/DMC + Aq DMF/DMC + 40% ZnCl2

• 60% ZnCl 2

Coagulation bath Washing Bath

• Advantage:

– Suitable for staple fibre.

– Both organic and inorganic solvent can be used – Low temp reqd.

– Higher production due to continue spgn.

Parameter Melt spgn Dry spgn Wet spgn

3 Heat of spgn High Very high Low

4 Spinneret hole 2 – many

explosion)

Toxic

thousand 300-900 20,000- 75,000

min

2500-3000 ft/

min

150-300 ft/min

Comparative features of melt, dry and wet spinning

•Production does not depend on climate & location.

•Quality & quantity can be controlled during production.

•Length & thickness can be controlled as per requirement.

•Staple length can be controlled as per requirement.

•Smoothness and high luster.

•Fiber processing is easier.

•High productivity and low cost.

Advantage of man-made fiber technology:

1 Fabrics made of MMF are difficult to stitch.

2 Low air permeability.

1 Yarn Manufacturing Technology

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