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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
Special Instruction: Special Instruction: 1. Fabric shrinkage must keep within ±5% 2. Color fastness should be 4-5 range 3. Pilling range 3 to 5 4. pH range 5.5 to 7 5. Fabric weight will be allowed ±02% 6. Fabric quality should be s per approved swatches & Lab-Dips. 7. Batch to batch color matching should be 4-5 8. Batch to batch “Shade Band Swatch” must be submitted for approval.
Production Parameters Process Temp(▫C) pH Time min M : L ratio Scouring - Bleaching 98 10-11 30 1:8 Enzyme Wash 55 4.5-5 30 1:8 Reactive Dyeing 60 10-11 60 1:8 (Light Shade) Reactive Dyeing 60 11-12 60 1:8 (Dark Shade) White Shade 98 10.5-11.5 30 1:8 Turquish color dyeing 80-90 11-12 60 1:8 Polyester dyeing 130 4-4.5 45 1:8
Dyeing Parameter: pH: Bleaching bath pH : 10.5 – 11 Neutralization or after bleaching pH : 5.5 – 6.5 Bio polishing bath pH : 4.5 Initial dye bath pH : 5.5-6.5 After alkali addition pH : 10.5 – 11 After dyeing pH : 5.0 – 6.0 Fixation bath pH : 4.5 – 5.5 Softener bath pH : 4.0 – 5.0 ( For color )
Dyeing Parameter: Temperature: For cotton Pretreatment : 98C For Cotton Biopolishing : 55C Cotton Dyeing: : (50-60)C During Turquise :80C During Isothermal :60C Red special : 60 C White dyeing : 80 C For Polyester Dyeing :130C For Cotton soaping : 98C Temperature during softening & fixing : 40C For cotton hot wash : (70-90)C For cotton acid wash : (50-60)C
Dyeing Parameter: A. pH During peroxide bleaching & scouring 9-11 During enzyme treatment 4.5-5 Before addition of leveling agent 6-6.5 Before addition of color softener 6-6.5 Before addition of white softener 4.5-5 Softener at stenter& de-watering 5.5-6 Silicon softener 5.5-6 Reactive dyeing 10.5-12 Disperse dyeing 4.5-5.5
Dyeing Parameter: B. Temperature For cotton scouring 95-100˚C For cotton bleaching 50-60˚C For cotton hot wash 70-80˚C For cotton acid wash 60-70˚C For cotton dyeing 80˚C ( For hot brand)/60˚C(For cold brand) C. Time For scouring and bleaching 60-90 mins For reactive dyeing 60-90 mins For disperse dyeing 60-90 mins
Amount Of Salt , Alkali & Fixation time On The Basis Of Shade%: Shade % Salt(g/l) Alkali(g/l) Fixing time(min) 0-0.1 30 10 20 0.1-0.5 30 15 30 0.5-01 40 20 40 1-1.5 50 20 50 1.51-2 60 20 60 2-2.5 70 20 60 2.5-5 80 20 60 Above 6 100 25 70 Black shade 100 10+0.5g/l NaOH 70
QUALITY ASSURANCE SYSTEM Quality is always a vital parameter for customers’ satisfaction. No matter what is the job you perform, but your contribution is also a matter of fact. Here the top management is concerned about that & thus build up a reasonable “Quality Control” department. Task(s) of Q.C. Department 1. Initial check (checking of yarn quality) 2. Final check (checking of yarn properties after dyeing, finishing & hard winding) 3. Initial check 4. Strength 5. Count (specially of melange) 6. T.P.I (specially of melange) Final Check 1. Strength 2. Shade (both of yarn & fabric) 3. Fastness (wash & rubbing) 4. Evenness of dyeing 5. Layer check 6. Waxing check
Calculation realted to dyeing floor: 39.37 fabric width no of Nozzle CycleTimt 1000 MachineCapacity Winch speed . GSM 39.37 Fabric width No of Nozzle Winch speed 10000 MachineCapacity CycleTime . Fabric GSM Re ( ) % quired Dye kg Shade FabricweightinKg g l required Total liquor / Re quired Chemicals 1000
There are some reasons related to arise those problem, are mentioned below: 1. More rejection of garments items due to fabric faults (lack of adequate and improper inspection.) 2. Short quantity production due to lack of full quantity finished fabric. 3. Dyeing & finishing department unable to supply full quantity finish fabric to garment section according to “Time and action” plan due to facing problem on batch to batch shade variation (out of tolerance limits); fabric width; GSM; shrinkage; spirality, dyeing faults. 4. More dyeing and finishing faults appear due to follow incorrect dyeing & finishing recipe & procedure. 5. Knitting section fail “Time and action” plan. 6. Grey GSM problem due to improper yarn count; stitch length, machine selection.
Dyeing Parameter & Calculation: Dyeing Parameter & Calculation: The things which influence the effective coloration of textile materials with reactive dye are called as parameters of dyeing. These include –Temperature, Time, Liquor ratio, pH of the bath etc. A brief description about them is given below Effects of Temperature: Temperature of the dye bath plays vital role for dyeing. Rise in temperature has a large effect on an increase in the diffusion rate of dyes into fabrics. Increasing of temperature increases the rate of dyeing & of the dye migration. Higher dyeing temperature ensures the good leveling & better penetration of dye in to the fibers. But the temperature depends on the types of dyes adapted in the dye bath. For Example-in case of hot brand dyestuff the dosing temperature of dye is 80ºC and for cold brand dye temperature is kept 60ºC.
Dyeing Parameter & Calculation: Effects of pH: In the case of most popular fiber reactive dyes, a high PH actually activates the cellulose (cot-ton) fiber, forming a cellulosed anion, which can then attack the dye molecule, leading to a reaction that produces a strong, permanent covalent bond. Without a high pH, the dye will not fix permanently to the cellulose fiber. For this reason Sodium Carbonate (Na2CO3) [Some time mixed alkali such as (NaOH + Na2CO3)] is used for no other reason than to increase the PH of the dye reaction, so that the fiber will react with the dye. Basically during the color addition, the PH of the bath remains at near about 6, but after adding alkali it goes rise to pH 11.4 & this is the critical stage in which the dye molecules fix up with the fiber. Effects of Time: The time for dyeing also the vital one. A specific Time adjusted with the temperature, very much needed for better dyeing. For this reason color dosing takes place in 20 minutes (may vary process to process) & Specific run time is set for dyeing.
Dyeing Parameter & Calculation: Effects of Material: Liquor Ratio (M:L): Dye bath exhaustion increases with the decreasing of liquor ratio. Dyeing at low liquor ratio decreases the amount of waste dyes & chemicals in the effluent. Because higher the liquor ratio greater the amount of g/l of chemicals which increases the volume of effluent. To get rid from this problem Then Air flow Dyeing machine is getting popular in our country which can dyeing at 1:3 Materials: Liquor ratio. But in case of Thies Jet Dyeing machine it can possible up to 1: 5 Materials: liquor ratio. Shrinkage: A dimensional change resulting in a decrease in the length or width of a specimen subjected to specified condition is known shrinkage. Spirality: If the Wales of the knitted fabric are not perpendicular to the course and skew to the right or left spirality occurs in the fabric. This creates serious problem, especially in the apparel industry.
Finishing & Finishing Target: Achieving finishing target of knit fabric means to achieve the finished fabric with all the quality or parameters that is required by the customer. In case of knit fabric, target quality refers to the shade, GSM, shrinkage, spirality, color fastness etc. When order is placed, at first fabric structure, GSM, shade is considered. Depending on the parameters yarn count, m/c gauge, stitch length, machine dia, yarn type are selected all those factors are related with target quality. Grey fabric gsm should be lower than finished gsm. In case of knitting fabric at least 15% weight will increase during wet processing. Grey gsm will depend on the shade percentage, lycra %, type of yarn used and type of finishing pequired for that particular fabric. For light shade stitch length will be more than deep shade. In case of spirality, it will depend on the yarn count, compactness, feeder no. of the knitting machine. If count (Ne) is high, compactness of the fabric is more and feeder no. of the m/c is lower than fabric spirality and shrinkage will be less.
Finishing & Finishing Target: Yarn count and m/c gauge are related to each other and if those two factors are not matched then faults will be occurred on the fabric. For example, 20’s for 20G/18G, 30’s for 24G, 40’s/28G will yield lower spirality and shrinkage. In case of wet processing, shade must be developed in the dyeing laboratory and should be approved by the buyer. The recipe that is developed in lab is used by reducing in quantity for bulk production. Because dye pick up percentage is always high in dyeing m/c. Shade should be kept in deeper condition before dropping of dye liquor from dyeing m/c. because shade could be lighter during soaping. In case of finishing process, padder pressure, temperature, fabric speed, chemicals and finishing line should be determine by considering the finishing target because, all those factors may affect fabric shade. But in case of open line, stenter machine is used, which may control most of the parameters in knit fabric. But fabric should be in open form. Thus open squeezer is used to slitting the fabric. Then the fabric is feed on stenter where chemicals can also be applied.
Finishing & Finishing Target: When fabric is unloaded from m/c water content is about 200% in case of knit fabric. Thus hydro-extractor, de-watering m/c are used before drying the fabric. Otherwise heat consumption for drying process will be huge and that is not cost effective. In this section finishing chemicals can be applied to the fabric. Drying machine is used to evaporate water remaining in the fabric after de- watering process and to obtain fully dried fabric. Fabric dia will reduce during relax drying process and tube fabric is finished in this machine. Thus tubular fabric dia should be kept more than the required finished dia in de-watering machine. This dia will be reduced in drying machine. After that tube compactor is finally used to achieve target quality of the fabric. gsm can be controlled up to 10%. Fabric shrinkage, spirality, Gsm, shade, bowing effect, slanting etc can be controlled by stenter m/c. Maximum 20% gsm can be controlled by stenter m/c. Fabric shade can be controlled by maintaining temp. if shade is dark then temp.
Finishing & Finishing Target: should be high and 15-20% light shade can be obtained. If shade is light in fabric then temp. should be lowered and silicon softener is used in large quantity.Then the fabric is finally finished with open compactor m/c. Maximun 14% gsm of the fabric can be controlled. If ultra-soft fabric is required by the buyer, then gsm of the fabric should be kept at least 5% more after finishing process. Softening action is done on the back side of the fabric and the fabric is again finished on stenter m/c. In case of brushing, the back side of the fabric is brushed. Loops of the fleece fabric are brushed. Fabric may feed on the m/c for 5-8 times until the target brushing action is achieved.
Finishing & Finishing Target: After all those operations, quality control process of the fabric is done in online and off-line process. In online process gsm, shade, shade variation, hole patta, bowing, slanting, oil mark, chemical spot etc are checked and graded with 4 points system. In off-line QC shrinkage, spirality, gsm, color fastness, wash fastness etc are done which are required by the buyer. Sometimes problem can appear such as shrinkage, spirality, gsm of the fabric which cannot be controlled by those finishing process. In this case fabric is wetted and tumble dried to overcome those problems. By this process, sample fabric is finished at first then required tests are done on the fabric. Sometimes it is not possible to control shrinkage, gsm, spirality, and other knitting faults due to knitting m/c and yarn. In this situation, the knitting department should take necessary actions to overcome those problems.
Finishing & Finishing Target: If any faults or quality problem is appeared due to dyeing or finishing the fabric should be reprocessed, such as re-dyeing, topping, stripping are done and finished again. But target should be to finish the fabric without re- processing. Above all those factors, target finished date must not exceed to finish the fabric. If the fabric is achieve with all the required quality within the target finished date then that will be said that we have achieved the finishing target of knit fabric for a particular batch.
Parameter Setting Pump Speed (Load) 70% Pump Speed (Next all) 80% Winch Speed (Load) 100m/min Winch Speed (Next all) 220m/min Nozzle Speed (For all) 50%
Table : GSM achievement for Elastane Single Jersey (Chocolate Color) By ISO Standard. Stenter GSM 160 160 163 158 Compactor/ Actual GSM 173 171 176 172 Target GSM Variation (%) 180 180 180 180 Remarks Pass pass Pass pass -3.89% -4.35% -2.25% -4.15%
Table : Achievent of colorfastness to wash for Chocolate Color By ISO Standard. Target grade Actual 4 – 5 4 – 5 4 – 5 4 – 5 Variation No No 1 No Remarks Pass Pass Fail Pass 4 – 5 4 – 5 3 - 4 4 – 5
Table : Achievent of colorfastness to rubbing for Chocolote Color By ISO Standard. Target grade Actual Dry Wet 4 – 5 3 to 5 4 4 – 5 3 to 5 5 4 – 5 3 to 5 4 4 – 5 3 to 5 4 Variation Remarks Dry Wet Dry 3 4 3 4 Wet No No No No 0.5 No 0.5 0.5 Pass Pass Pass Pass
Table : Achievement of shrinkage for Es. Single Jersey (Chocolate Color) By ISO Standard. Target Length ± 5% ± 5% ± 5% ± 5% Actual Length -5% -4% -4.5% 5% Variation Length Width No No No No Remarks Width ± 5% ± 5% ± 5% ± 5% Width -2% -3% -2% -2.5% No No No No Pass Pass Pass Pass
Table 4-24: Physical test report for Navy color (Buyer: S.Oliver)
GSM Achievement Sample Stenter GSM 168 Finish GSM 185 Target GSM 200 Variation (%) -7.5 Remarks Elastane Single Lacoste (Aqua color) Elastane Single Lacoste(Chocolate color) Elastane Single Lacoste(Black color) Pass(Speci al Case) pass 160 173 180 -3.89 185 193 200 -3.5 pass Single Jersey(Navy color) 158 160 160 0 pass
Color Fastness Wash Achievement Sample Target grade Actual Variation Remarks Elastane Single Lacoste(Aqua color) 4 - 5 4 - 5 No Pass Elastane Single Lacoste(Chocolate color) 4 - 5 4 - 5 No Pass Elastane Single Lacoste(Black color) 4 - 5 4 - 5 No Pass Single Jersey(Navy color) 4 - 5 4 0.5 Pass
Color Fastness to Rubbing Achievement Sample Target grade Dry Wet Actual Dry Wet 4 – 5 3 Variation Dry Wet No No 0.5 No Pass Remarks Elastane Single Lacoste(Aqua color) Elastane Single Lacoste(Chocolate color) Elastane Single Lacoste(Black color) Single Jersey(Navy color) 4 – 5 3 - 5 Pass 4 – 5 3 - 5 4 3 4 – 5 3 - 5 4 3 0.5 No 0.5 No Pass Pass 4 – 5 3 - 5 4 3
Shrinkage Achievement Target Actual Variation Remarks Sample Length Width ±5% ±5% Length Width -6.3% -2% Length Width -1.3% No Elastane Single Lacoste (Aqua color) Elastane Single Lacoste (Chocolate color) Elastane Single Lacoste(Black color) Single Jersey(Navy color) Pass(spec ial case) Pass ±5% ±5% -5% -2% No No ±5% ±5% -2.4% -2.9% No No Pass ±5% ±5% -5% -3% No No Pass
Control parameters 1. Liquor ratio by analogue control or electromagnetic flow meter 2. Time/temperature profile 3. pH measurement, monitoring and adjustment using retractable electrode 4. Rate of change of pH 5. Conductivity 6. Specific gravity 7. Redox potential 8. Liquor flow rate 9. Rope circulation time 10.Addition time and profile for dyes, auxiliaries and chemicals
Control functions in continuous processing 1. Bath temperature control 2. Fabric temperature control 3. Steamer pressure 4. Water and chemical flow 5. Liquor pH control 6. Conductivity of liquor or fabric 7. Specific gravity of process liquor 8. Pad pressure and nip expression 9. Compensator pressure 10. Liquor level 11. Fabric speed 12. Chemical dosing 13. Automatic filling of baths 14. Data for steam, water, chemical and electricity consumption 15. Process visualisation/schematics 16. Automated mangle rinsing 17. Automated I R predryer heat control to speed up batch changeover 18. Control of oxidation baths 19. Control of final fabric pH 20. Rapid substitution of operating process details to cope with changes in substrate quality being processed
Anticipated benefits from investment in control technology Factor Shade reproducibility Levelness Minimal damage of the substrate RFT dyeing Low liquor ratios Water recovery and reuse Low- temperature dyeing Controlled equipment Consistent dye and chemical weighing and dispensing Reliable recipe calculation Shorter cycle times Less downtime and less cleaning through scheduling Reduced manning levels Rationalised/standard products Better stock control Instrumental colour measurement Benefit Improved quality Savings in resources (steam, water, effluent, power) Elimination of errors Productivity increases Savings in dyes and chemicals Improvements in productivity and reproducibility
Control functions for dyeing machine Function Requirement Machine fill Raise to initial temperature at rapid rate of rise Circulate material or liquor Raise to top temperature at controlled ramp Flow reversal sequence Holding time at top temperature Controlled cooling ramp Drain Actuated valve and level sensor Actuated steam valve and temperature sensor Controlled electric motor or pump Actuated valve on cooling water Actuated valve on drain
Most important factors for polyester fabric dyeing 1. Substrate dyeability 2. Heat treatments above 150°C before dyeing 3. Fabric preparation 4. Dyebath pH 5. Metal-ion content of the dyebath 6. Dye concentration
Factors requiring control in the dyeing of sewing thread Factors of prime importance Dyeability of substrate Heat-setting conditions (polyester): time, temperature and tension Dry weight of substrate Colour value of dyes Weight of dye Moisture content of dye Accuracy of dissolving or dispersing dye Dyebath temperature Liquor-to-goods ratio Factors of major importance Weight of electrolyte (cotton dyeing) Weight of auxiliary product Yarn construction (e.g. twist) Degree of bleaching Time of dyeing pH of dyeing Factors of minor importance (cotton) Degree of mercerisation (cotton) Size content Temperature of drying before dyeing Water quality
Summary of important factors in dyeing processes requiring control to minimise variability in colour difference Factor Variability ∆E(CMC) Visual limit of trained colourist 0.6 Substrate variability up to 4.0 Water supply variation up to 3.0 Instability of dye solutions and dispersions 3.0 to 5.0 Variations in dye weighing of 2.5% 2.5 Quality control assessment of dyeings 0.15 Batch levelness 0.2 Reproducibility in bulk 0.2 Laboratory dyeing reproducibility 0.12 Laboratory to bulk reproducibility 0.3
Ecological parameters: Ecological parameters: Now all the Customers are asking for Ecological Parameters. Now European Buyers are stressing this. Following are main Ecological Parameters to be considered. pH range Formaldehyde levels Extractable heavy metals Chlorinated phenols Pesticides Chlorinated Organic carriers Biocide finishes Flame retardant finishes Colour fastness to Water Colour fastness to acid & alkali perspiration Colour fastness to wet & dry rubbing Colour fastness to saliva Emission of volatile chemicals Other specific parameters as required by the customers
H Process Scouring- bleaching Enzyme wash Temp. (C) 100 P Time(min) 30 M:L ratio 1:8 10.5 50 70 60 5 30 10 60 1:8 10.5 1:6 Reactive dyeing light shade Reactive dyeing med. to dark shade Turquise color dyeing Polyester stripping Cotton stripping Polyester dyeing Cotton whitening 60-65 10.5 60 1:6 70-80 10.5 90 1:6 90 4.5 30-45 1:8 100 11 30 1:8 130 4.5-5.5 60 1:8 100 30 1:6
