Knit dyeing faults and it’s remedies

1. WELCOME TO THE PRESENTATION

2. PREPARED BY ©right Name : MAZADUL HASAN SHESHIR ID: 2010000400008 Batch: 13th Batch (Session 2009-2013) Department: Wet Processing Technology Email: mazadulhasan@yahoo.com Blog: www. Textilelab.blogspot.com Southeast University Department of Textile Engineering

3. INTRODUCTION  Dyeing is a process of treating fabrics with dye liquors which contains both dyestuffs and chemicals and fixing the dyes in the fabric subsequently.  In discussing faults which can be attributed to dyer and finisher, it is necessary first to have a general conception of some of the major operations to which goods are subjected after they are received by the finisher of wet processing .

4. OBJECTIVES  To know about the different types of wet processing faults.  To know about the causes of different types of wet processing faults.  To know about the remedies of different types of wet processing faults.  To know about the pre-treatment process of textile goods.  To know about the wet process of textile goods.  To know about the finishing process of textile goods.  To know about the different types of wet processing machineries.  To know about the job sequence of wet processing industry.

5. FLOW CHART OF KNIT DYEING Grey Fabric Stitching Singeing De-sizing Scouring and Bleaching Dyeing Finishing Tube Fabric Open Fabric Dewatering Slitting Dryer Stanter Compector Compactor Inspection Packing Delivery

7. Description of wet processing faults has been found in knit dyeing: Faults Name Faults Sample Incomplete Scouring Causes Remedy Too Low concentration of scouring chemical Too Low scouring temperature and time Ineffective surfactant / wetting agent Optimum concentration of scouring chemical. Optimum scouring temperature and Time. Effective surfactant / wetting agent.       

8. Faults Name Faults Sample Low degree of whiteness Causes Remedy In adequate concentration of H2O2. Too low bleaching pH. Too low bleaching time and temperature. Optimum concentration of H2O2 Optimum bleaching pH. Optimum time and temperature.      

9. Faults Name Faults Sample Effect of H2O2 residues Causes Remedy H2O2 residues remove not properly H2O2 killer agent dosing not properly Not properly H2O2 killer runtime Running in alkaline condition. H2O2 residues remove properly H2O2 killer agent dosing properly Properly H2O2 killer runtime H2O2 killer agent runtime must in acidic condition.        

10. Faults Name Faults Sample Effect of Hairiness Causes Remedy Not properly enzyme dosing High temperature enzyme Runtime pH not properly controlled Short runtime of enzyme wash When spoil of enzyme activity Required amount of enzyme dosing Temperature control properly pH controlled must be 4.5- 4.7 Full time of enzyme run Properly enzyme stored in below 25tem.          

11. Faults Name Faults Sample Barrie Causes Remedy It may be caused by variation in the size of the filling yarn By the differences in tension of either the filling or warp yarn Variation in drawing ratio in spinning Temperature variation during fixation process Exactly size of filling yarn Properly tension of yarn Proper thermo fixation process Selecting dyes and leveling agent which are not affected by the temperature variations.        

12. Faults Name Faults Sample Shade bar Causes Remedy It may be caused by a change of filling bobbin in the loom or a loom stop and start up. It is a horizontal band of a different hue running across the fabric. Properly change of bobbin.   

13. Faults Name Faults Sample Uneven dyeing Causes Remedy Uneven pretreatment (uneven scouring & bleaching). Improper color dosing Using dyes of high fixation property. Uneven heat-setting in case of synthetic fibers. Lack of control on dyeing m/c. By ensuring even pretreatment By ensuring even heat-setting in case of synthetic fibers. Proper dosing of dyes and chemicals. Proper controlling of dyeing m/c.         

14. Faults Name Faults Sample Line mark Causes Remedy Long time store in the floor Dyeing process not properly Extra tension on the fabric Properly stored in the after dyeing Exactly dyeing process control Tension less fabric run in the dye bath      

15. Faults Name Faults Sample Batch to Batch Shade variation Causes Remedy Use standard dyes and chemicals. Maintain the same liquor ratio. Follow the standard pretreatment procedure. Maintain the same dyeing cycle. Identical dyeing procedure should be followed for the same depth of the shade.    Fluctuation of Temperature. Improper dosing time of dyes and chemicals. Batch to batch weight variation of dyes and chemicals. Dyes lot variation.      

16. Faults Name Faults Sample Dye spot Causes Remedy Improper Dissolving of dye particle in bath. Improper Dissolving of caustic soda particle in bath. By proper dissolving of dyes and chemicals. By passing the dissolved dyestuff through a fine stainless steel mesh strainer, so that the large un- dissolved particles are removed.    

17. Faults Name Faults Sample Crease mark Causes Remedy Poor opening of the fabric rope. Shock cooling of synthetic material If pump pressure and reel speed is not equal. Due to high speed m/c running. Maintaining proper reel speed and pumps speed. Lower rate rising and cooling the temperature. Reducing the m/c load. Higher liquor ratio.        

18. Faults Name Faults Sample Roll to roll variation or meter to meter variation Causes Remedy Use standard dyes and chemicals. Proper m/c speed. Use of soft water.    Poor migration property of dyes. Improper dyes solubility. Hardness of water. Faulty m/c speed, etc.    

19. Faults Name Faults Sample Thick –thin yarn Causes Remedy After dyeing this type of problem cannot be removed but can be avoided by not mixing the thick/thin yarn in a single fabric.  If thick/thin yarn is used for making a fabric. Used of immature fiber. Used of short staple length of fiber.   

20. Faults Name Faults Sample Off shade Causes Remedy Properly select of dye. Correctly fabric lot selection.   It refers to color that does not exactly match the standard or the prepared sample. This may be due to faulty dyed foundation or application or may be due to variation in dye lot.  

21. Faults Name Faults Sample Insufficient hydrophilic Causes Remedy Insufficient removal of grease, wax and sizing film which gives hydrophobic characteristics to the fabric. When a fabric with un uniform hydrophilic is dyed, areas with different lower / hydrophilic results in a lighter shade are obtained due to the lack of absorption of the dye liquor. To avoid this a thorough pre-treatment is a must,   Wetting agent can be used in dyeing liquor. 

22. Faults Name Faults Sample Bowing Causes Remedy Uniform sewing is required. Equal width fabric is required. Proper tension fabric passes in compactor.    Woven filling yarns lie in an arc across fabric width; in knits the course lines lay an arc across width of goods. Establish standards of acceptance .Critical on stripes or patterns not as critical on solid color fabrics.  

23. Faults Name Faults Sample Compacting crease Causes Remedy Minimum required of Teflon pressure. Exact setting of tension roller. Exact setting of temperature in cylinder.    Excessive apply on Teflon pressure. Less tension roller. Uneven temperature of two cylinders.   

24. Faults Name Faults Sample Water spot Causes Remedy Fixation with a few drop of water on specific area of dyed fabric Proper fixation  

25. Faults Name Faults Sample Poor washing fastness Causes Remedy Optimum washing off. Use of cationic fixing agent or other fastness improving after treatment.   Inadequate washing of hydrolyzed dye. Inadequate removal of loosely retained dye. Inherent low fastness properties of the dye.   

26. Faults Name Faults Sample Oil & Grease Spot Causes Remedy During dyeing and finishing process sometimes oil and grease may fall on fabric which may cause oil and grease spot on the dyed fabric. Due to careless transport of dyed or finished fabric. Must be careful about oil and grease during dyeing and finishing process. Must be careful about the transportation of dyed or finished fabric. With immediate application of spot –lifter.     

27. Faults Name Faults Sample Pilling effect Causes Remedy Pilling is a common fabric occurring on knitted and woven fabrics. In producing a yarn fibers tightly twisting produce a serviceable yarn. When short stable fibers are mixed into the yarn the result is a yarn that will not together. The short staple fibers will separate from the yarn and curl up in a ball,- forming what is referred to as a pill. Pilling is accentuated by the friction of normal wear, washing and routine dry cleaning.  Exactly maintain of enzyme wash. Evenly mixing of short staple fibers. Properly twisted of yarn.     

28. CONCLUSION Two months industrial training at Alim knit tex (Mondol Group) Ltd, Metro Knit and Dying Mills Ltd, Square Knit Fabrics Ltd. were a part of B.Sc. in Textile Engineering course. During the training period the whole 60 days were segmented and scheduled to a systematic routine. There was different faults operation in textile wet processing. It should be mentioned that Alim knit tex (Mondol Group) Ltd, Metro Knit and Dying Mills Ltd, Square Knit Fabrics Ltd. are 100% export oriented knit dyeing industry .To produce a quality product above all export quality it could be desirable that the process should be high standard. Here we have some limitations in our training period, and two months are not enough time to complete the knowledge about the textile terms.