Drawing man made fiber

Drawing

1. Module 4

2. The process of adding Inorganic pigments or colorants in melted polymer or spinning solution is called mass or spin or dope or solution dyeing .

3. Properties of Mass coloration process: Stable & superior color-fast yarn is produced Better color reproducibility and consistency No drying, re-winding or water usage Less labor required and less carbon footprint . Polymer waste at start up and shut down or color change (extreme flushing) Less flexible Limited shades and difficult to adjust to fashion changes

4. For Manmade Fibers Defini t ion Types of Drawing Draw Ratio/Stretch Ratio Draw-Textu r izat i on

5. Drawing The process by which the yarn/ fiber is elongated by passing it through a series of pair of rollers, in which each pair moving faster than the previous one is called Drawing or Stretching

6. Characteristics of Manmade Fibers Irregularl y placed molecules (amorphous) with poor thermal and chemical stability Low resistance to ageing High elongation/deformation Low tensile strength

7. Draw Ratio, R V2>V1

8. Object ive s 1.To increase strength 2.To increase orientation and crystallinity To reduce elongation at break To reduce creep To remove brittleness and instability of the fiber

9. Drawing during spinning (POY) Drawing in unplasticized condition (hot, PET, 80 o C; cold, nylon 6/66) Drawing in plasticized condition (Acetate/triacetate) Draw-warping (for flat yarn) Draw-texturization (DTY) FDY method (≈6,000 m/min, flat yarn, directly used in weaving/knitting) H4S method (10,000 m/min, High Speed Spinning Stretching Steaming, Polyamide6/Nylon6= PA6) Wet stretching (during wet spinning)

10. Draw Ratio: The ratio of surface speeds between drawing rollers and feeding rollers is called draw ratio [≈1.2 (cellulosics), 3-5 (thermoplastics), 10 (acrylic)]. Depends on types of fiber, production process Fiber end use characteristics. Higher draw ratio usually used for technical textiles applications . Residual draw ratio: The draw ratio , up to which the yarn can be further drawn to make it suitable for textile application (FDY) is called residual draw ratio. Stretch ratio: The ratio between drawn and undrawn length is called stretch ratio. Stretch ratio Is slightly lower than draw ratio depending on elastic recovery.

11. The partially drawn yarn (POY) has to undergo a further drawing where both drawing and texturization are carried out in a single process. Two types: Sequential (first drawing and then texturization) and Simultaneous (PES/PA =polyester/polyamide , drawing in the texturing zone)

12. Unplasticized condition: In cold unplasticized condition - If the Tg of fiber is about room temperature, then no extra heat is used. At first, undrawn yarn is passed between two control rollers and then arranged into snubber pin and stretched through the draw roller. In hot unplasticized condition- A heater is used between the pin and draw roller and heated at suitable temperature. For example the draw temperature is 80 C for Polyester (Terylene) and Acrylic.

13. Control Roller Undrawn yarn Heater(Optional) Snabber Pin Draw Roller Drawn yarn Fig: Drawn yarn of unplastisized Process.

14. Plasticized condition: In this process, at first the undrawn yarn is passed through the two pair stretching roller which is taken in a plasticizing bath. Then it is rinsed and wound in a bobbin.

15. Wet Stetching: Goddet controlled wet stretch: in this process, the undrawn yarn is passed and drawn by a Goddet wheel directy. Snubber controlled wet Stretch: in this process the undrawn yarn is first arrange into a snubber pin & then stretched drawn by a goddet wheel.