55978325 dyeing-problem-ppt
- 1. PRESENTATION ON DYEING PROBLEMS AND REMEDIES PRESENTED BY, FAHMIDA SULTANA; ID#073-23-653 SADDAM HOSSAIN BHUIYAN; ID#073-23-626 DIPAK KUMAR SARKER; ID#073-23-568 S.M.MOHIUDDIN; ID#073-23-657 SABBIR AHMED MAJUMDER; ID#073-23-592
- 2. Dyeing is the process of adding color to textile products like fibers, yarns, and fabrics. Dyeing is normally done in a special solution containing dyes and particular chemical material. After dyeing, dye molecules have uncut Chemical bond with fiber molecules. The temperature and time controlling are two key factors in dyeing. The stages in the processing of textile dyeing:
- 3. Pretreatment problems : 21% Dyeing & Printing problems : 23% Finishing problems : 11% Biological & machine problems : 24% Diverse problems : 22%
- 4. Pretreatment that is known accurate composition. The chemicals are used for pre-treatment of all fibers and are used for removing dirt, oil, fatty and waxy impurities. Moreover, these chemicals also act as a mild stain remover. 70% of the problems due to dyeing can be attributed to the preparatory pretreatment, because it is the first stage in dyeing processing. So, dyeing depends on its effectiveness and efficiency. The dyeing process which follows pretreatment depends on a number of parameters like: 1. Time 2. Temperature 3. Conc. of chemicals and auxiliaries selection 4. pH of the process etc.
- 5. Pretreatment problems Poor absorbency. Catalytic damage/poor fluidity. Stains. Moire effect. Shade change from selvedge to selvedge. Shrinkage/distortion. Creasing/chafe marks. Handling. Inferior brightness/luster. Cloudy dyeing. Skitteriness. Pale areas. Dark spots. Rope marks.
- 6. Pretreatment remedies Use of specialty chemicals. Select suitable heat setting temperatures. Thorough relaxation of the material. Controlled tension and uniformity of batching during pretreatment. Checking for rough patches in the machine. Carry out lab tests. Carry out preliminary tests with material. Quality inspection before and after pretretment.
- 7. Dyeing problems 1. Unlevelness(due to dyeing conditions) ‡ Ending problems ‡ Cloudy dyeing ‡ Pale areas 2. Unlevelness(due to material) ‡ Barriness 3. Unlevelness(due to other reasons) ‡ Skitterness ‡ Listing ‡ Pale areas after dyeing 4. Reproducibility ‡ Deviation of shade ‡ Dyeing too pale ‡ Precipitates in the dye bath ‡ Change of shade 5. Fastness properties ‡ Unexpectedly poor light fastness ‡ Unexpectedly poor wet and rub fastness 6. Spots, marks ‡ Precipitates in the dye bath ‡ Singeing droplets ‡ Change of shade (e.g. blue spots in brilliant red shades) ‡ Dark spots ‡ Specks ‡ Dirt spots
- 8. Dyeing problems 7. Appearance of the goods y Dimensional stability (shrinkage) y Creasing y Chafe marks y Stitch distortion (knits) y Moire effects (on beam) y Luster y Handle y Pilling (staple fibers) 8. Other problems y Difficulty with heavy shades on fine denier yarn y Soiling of machine y Frosting on goods y Poor running of material in subsequent processing 9. Thermosol dyeing problems y Listing y Two-sidedness y Dark or pale selvedges y Barry dyeing y Spots, specks y Ending y Pale points of intersection y Foam formation y Frosting
- 9. Major 10 causes of dyeing problem 1. Inadequate pretretment. 2. Wrong dyeing program. 3. Irregular tension. 4. Dye sensitivity. 5. Mechanical affect,Chemical affect & Material affect. 6. Stained adjacent fiber. 7. Migration due to chemicals, wrong dyeing program, drying. 8. Use of volatile carrier, silicon, dispersant. 9. Residue of alkali, boiling agent. 10. Fiber surface, fiber origin & physical change in fiber due to local pressure, temparature.
- 10. Major 10 remedies of dyeing problem 1. Optimizing a dyeing process. 2. Select dyes with better dispersion stability, use efficient dispersants. 3. Adjust the machine more carefully 4. Use special chemicals, antifoamers. 5. Pay attention to perfect pretreatment. 6. Select special dyes (smallll-molecule) . 7. Use silicone-free defoamers & Select suitable carriers, use overhead heating in the machine. 8. Pay attention to cleanness in the machine 9. Check temperature and air current in drying machine. 10. Avoid migration by using lowest possible pickup and a suitable migration inhibitor.
- 11. Fabric defects due to dyeing problems A.dyeing of cellulosics Defect Cause Remedies 1.Specky/patchy dyeing Water drop on fabric & too Avoid water drop & use much foaming. defoamer. 2.Dark colored spot Incompatibility & too much Select proper dyestuff& check high dyestuff concentration. the solubility of dyestuff. 3.Dark or light selvedges Non uniform batching . Proper batching. 4.Center of selvedge variation Uneven wearing out of rolls Unifrom expression from of padding mangle padding mangle & unifrom &temparature variation. temparature. 5.Face to back variation Migration during Ensure working of all the fan intermediate drying. in dryer. 6.Oxidation patches in vat Improper or premature Take proper care during dyeing oxidation oxidation. 7.Bronginess & white marks Presence of free sulphur in Use sodium sulphate. in sulphur dyeing the dye bath
- 12. Fabric defects due to dyeing problems B.dyeing of polyester component of blended fabrics Defect Causes Remedies 1.Perforetion mark Inadequate leader cloth on to Use adequate leader cloth. the beam 2.Moire effect Too high tension during Proper tension during batching and inadequate heat bathing &poor heat setting of setting. fabric prior to dyeing. 3.Darker dyed selvedges Improper over lapping. Give proper overlapping. 4.Crush mark in jet dyeing Improper jet diameter. Depending upon fabric quality. 5.Oily stains Use of wrong type of Use proper defoamer defoamer. particularly when dyeing on rapid jet dyeing m/c. 6.Poor light fastness Presense of carrier in dyed Though removal of carrier. fabric 7.Barre dyeing Basic difference in the Take appropriate preventive polyester component measure to avoid mix up of particularly when using weft. textured filament weft.
- 13. Yarn defects due to dyeing problems Yarn defects are- ‡ Strength loss ‡ Harsh handle ‡ Channel building ‡ Unlevel dyeing ‡ Poor batch to batch reproducibility ‡ Package deformation & yarn abrasion ‡ Shade variation in Inner, Middle & Outer layer
- 14. Yarn defects due to dyeing problems Remedies for defect in yarn- 1. Package density & size: A uniform package density and size has to be ensured . 2. Angle of winding: Good winding produces a package of even densities with good running off properties & minimum of end breakage. Package with cross winding are preferable. 3. Perforation of spindle: Choking of perforation on spindle hinders smooth & uniform flow of liquor leading to uneven results. 4. M:L Ratio: A proper MLR has to be maintained during dyeing for consistency of batches. 5. Pump pressure: The change in pressure after reversal of cycle should not be significantly high. Necessary action has to be taken for smooth reversal & prevention of choking of pumps. 6. Entrapped air: Complete air removal has to be ensured prior to pressure build up for uniform results. 7. pH, Temp. & Time: Optimum values of those parameters have to be maintained during every stage of processing for best results.
- 15. 5 tips for remedies of dyeing problem 1. Right first time and all the time right. 2. Maintaining a competative edge is to lay emphasis on ³Quality´. 3. Fullest knowledge on basic facts. 4. Before find a solution of a problem find the cause. 5. Process control,which is one of the most effective manegerial tool.
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