Spinning process

melt, dry, wet spinning process

1. Spinning process Presented by : Shubham Tiwari M.Sc Polymer science Roll no. 26

2. Content Introduction of fiber Classification of fibres Types of Spinning technology Spinneret Melt flow Dry flow Wet flow

3. Introduction of fibre Fibre having a length at least 100 its Diameter. OR Substance that is significantly longer its width. There are two types of fibres A)Natural fibber's B)Man made/synthetic fibre's

4. Fiber structures

5. Classification of Fiber Natural fiber Man made/synthetic Plant/ vegetable Animal fiber Menarl fiber Cotton Flax Jute Linen etc Silk Mohair wool Asbestos synthetic inorganic Re generated Nylon Polyester Acrylic Spandex Polyvinyl derivative Glass Metallic Ceramic Cellulose acetate Rayon proteins viscose

6. Introduction of spinning process Spinning is a manufacturing process for creating polymer fibres. There are many types of spinning: wet, dry, melt, gel, and electrospinning. It is a specialized form of extrusion that uses a spinneret to form multiple continuous filaments.

7. Types of spinning process Melt spinning Dry spinning Wet spinning

8. Spinneret A spinneret is a device used to extrude a polymer solution or polymer melt to form fibers. Streams of viscous polymer exit via the spinneret into air or liquid leading to a phase inversion which allows the polymer to solidify. The individual polymer chains tend to align in the fiber because of viscous flow.

9. Material: Au-Pt, Tantalum, Stainless steel, others Application: Textile, Industrial yarn Hole size: Round/irregular-shaped hole range 0.03mm dia to 0.3mm dia

10. Melt Spinning Melt spinning is used for polymers that can be melted. The polymer solidifies by cooling after being extruded from the spinneret. Nylon , olefin , polyester , saran , and sulfar are produced via this process Melt Spinning (It is used for polymers that can be melted easily.) Melt spinning uses heat to melt the polymer to a viscosity suitable for extrusion. This type of spinning is used for polymers that are not decomposed or degraded by the temperatures necessary for extrusion. This method is used by 70% of the fibers.

11. In melt spinning, the filaments are normally drawn down, or stretched, just downstream of the spinneret holes.

12. The stretch is of the order of 2 to 3x, so the spinneret hole may be 50 to 75% larger than the filament diameter when it is first cooled.

13. Process In melt spinning, polymer is heated and it melts to form a liquid spinning solution or dope.  Chips of polymers are fed to a hopper which is heated. There is a grid (sieve) at the base which permits only molten liquid to pass through. Then the solution is purified by filter. The molten polymer is extruded at high pressure and constant rate through a spinneret into a relatively cooler air stream that solidifies the filaments. Finally the filament yarn either is immediately wound onto bobbins or is further treated for certain desired characteristics or end use.

14. Quenching/cooling system Cooling of fibre’s is three types. Cross flow quenching. In flow quenching. Cut off quenching.

15. Cross flow quenching. Universally this method is used for fine and large deniess & an for round and rectangular spin packs. But limitation that in this type only 25% of air could be used for the purpose of quenching and rest 75% goes as waste.

16. 2. In-flow quenching Air flow out side stream radially and symmetrically distributed over filaments which must be arranged in a ring shape.

17. 3. Cut-off quenching Is used for filaments yarns of high denies and for spinning of staple fibres.

18. Advantages of Melt Spinning: Can be used for both staple and continuous filament. Direct and simple process. No environment pollution. High production speed (2500-3000) ft/min. Low investment cost. Disadvantage of Melt Spinning: Required more proper maintained of machine. Heat of input is high.  Only for those polymer’s which having stability of melt in spinneret . Moisture content not exceed 0.05% by wt. of nylon and 0.005% for PET

19. Dry spinning: A solution consisting of a fiber-forming material and a solvent is extruded through a spinneret. A stream of hot air impinges on the jets of solution emerging from the spinneret, the solvent evaporates, and solid filaments are left behind.

20. Dry spinning process flow chart

21. Process In dry spinning, a volatile solvent is used to dissolve the raw materials and form a salutation. Then the solution is purified by filter. The solution is extruded through a spinneret into a warm air chamber where the solvent evaporates, solidifying the fine filaments. Finally the filament yarn either is immediately wound onto bobbins or is further treated for certain desired characteristics or end use.

22. Stretching of the fibers provides for orientation of the polymer chains along the fiber axis. Cellulose acetate (acetone solvent) is an example of a polymer which is dry spun commercially in large volumes.

23. Example: Dry spinning is used in the production of acetate, triacetate, and some acrylic, spandex, and vinyl (PVC,PVA) fibers.

24. Advantages: Yarn does not require purification Disadvantages: Flammable solvent hazards. Solvent recovery. Slow (200-400 yds/min).

25. Wet Spinning: A solution consisting of a fiber-forming material and a solvent is extruded through a spinneret. A stream of hot air impinges on the jets of solution emerging from the spinneret, the solvent evaporates, and solid filaments are left behind. This is the oldest, most complex and also the most expensive method of man-made yarn manufacture. This type of spinning is applied to polymers which do not melt and dissolve only in non-volatile or thermal unstable solvents.

26. Fig: Wet Spinning process

27. Process : In wet spinning, a non-volatile solvent is used to convert the raw material into a solution. The solvent is extruded through the spinneret either by simply washing it out or by a chemical reaction between the polymer solution and a reagent in the spinning bath. After extrusion, the solvent is removed in a liquid coagulation medium. Finally the filament yarn either is immediately wound onto bobbins or is further treated for certain desired characteristics or end use.

28. Fig: Wet Spinning process

29. Example: Wet spinning is used in the production of aramid, Lyocell, PVC, PVA, viscose rayon, spandex,kavelar , acrylic and modacrylic fibers.

30. Advantages: Large tows can be handled. Disadvantages: Slow (70-150 yds/min). Washing to remove impurities. Solvent and chemical recovery.

31. Thank you