Dyeing parameter

Dyeing Parameter

Name : MAZADUL HASAN SHESHIRID: 2010000400008Batch: 13th Batch (Session 2009-2013)Department: Wet Processing Technology Email: [email protected]: www. Textilelab.blogspot.com Southeast UniversityDepartment of Textile Engineering

PREPARED BY ©right

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.

Special Instruction:

Process Temp(▫C) pH Time min M : L ratioScouring - Bleaching 98 10-11 30 1:8

Enzyme Wash 55 4.5-5 30 1:8

Reactive Dyeing

(Light Shade)

60 10-11 60 1:8

Reactive Dyeing

(Dark Shade)

60 11-12 60 1:8

White Shade 98 10.5-11.5 30 1:8Turquish color dyeing 80-90 11-12 60 1:8

Polyester dyeing 130 4-4.5 45 1:8

Production Parameters

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. pHDuring peroxide bleaching & scouring 9-11During enzyme treatment 4.5-5Before addition of leveling agent 6-6.5Before addition of color softener 6-6.5Before addition of white softener 4.5-5Softener at stenter& de-watering 5.5-6Silicon softener 5.5-6Reactive dyeing 10.5-12Disperse dyeing 4.5-5.5

Dyeing Parameter:

C. TimeFor scouring and bleaching 60-90 minsFor reactive dyeing 60-90 minsFor disperse dyeing 60-90 mins

B. TemperatureFor cotton scouring 95-100˚CFor cotton bleaching 50-60˚CFor cotton hot wash 70-80˚CFor cotton acid wash 60-70˚CFor cotton dyeing 80˚C ( For hot brand)/60˚C(For cold brand)

Dyeing Parameter:

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 SYSTEMQuality 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. Department1. Initial check (checking of yarn quality)2. Final check (checking of yarn properties after dyeing, finishing & hard

winding)3. Initial check4. Strength5. Count (specially of melange)6. T.P.I (specially of melange)

Final Check7. Strength8. Shade (both of yarn & fabric)9. Fastness (wash & rubbing)10. Evenness of dyeing11. Layer check12. Waxing check

39.37 1000

.

Machine CapacityWinch speed

GSM fabric width no of Nozzle Cycle Timt

39.37 10000

.

Machine CapacityCycle Time

Fabric GSM Fabric width No of Nozzle Winch speed

Re ( ) %quired Dye kg Shade Fabric weight in Kg

/Re

1000

g l required Total liquorquired Chemicals

Calculation realted to dyeing floor:

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: 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.


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.


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.


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.


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.


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.


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%

Scouring & Bleaching Curve

Color Dosing Curve

Washing Curve

Order Sheet

Table : GSM achievement for Elastane Single Jersey (Chocolate Color) By ISO Standard.

Stenter GSM Compactor/ Actual GSM Target GSM Variation (%) Remarks 160 173 180 -3.89% Pass 160 171 180 -4.35% pass163 176 180 -2.25% Pass158 172 180 -4.15% pass

Table : Achievent of colorfastness to wash for Chocolate Color By ISO Standard.

Target grade Actual Variation Remarks 4 – 5 4 – 5 No Pass 4 – 5 4 – 5 No Pass 4 – 5 3 - 4 1 Fail4 – 5 4 – 5 No Pass

Table : Achievent of colorfastness to rubbing for Chocolote Color By ISO Standard.

Target grade Actual Variation Remarks Dry Wet Dry Wet Dry Wet

Pass 4 – 5 3 to 5 4 3 0.5 No 4 – 5 3 to 5 5 4 No No Pass4 – 5 3 to 5 4 3 0.5 No Pass4 – 5 3 to 5 4 4 0.5 No Pass

Table : Achievement of shrinkage for Es. Single Jersey (Chocolate Color) By ISO Standard.

Target Actual Variation Remarks Length Width Length Width Length Width

Pass ± 5% ± 5% -5% -2% No No ± 5% ± 5% -4% -3% No No Pass± 5% ± 5% -4.5% -2% No No Pass± 5% ± 5% 5% -2.5% No No Pass

Table 4-24: Physical test report for Navy color (Buyer: S.Oliver)

Stenter Machine:

Compactor Machine:

GSM Achievement

Sample StenterGSM

FinishGSM

TargetGSM

Variation(%)

Remarks

Elastane Single Lacoste (Aqua color)

168 185 200 -7.5 Pass(Special Case)

Elastane Single Lacoste(Chocolate color)

160 173 180 -3.89 pass

Elastane Single Lacoste(Black color)

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 gradeDry Wet

ActualDry Wet

VariationDry Wet

Remarks

Elastane Single Lacoste(Aqua color)

4 – 5 3 - 5 4 – 5 3 No No

Pass

Elastane Single Lacoste(Chocolate color)

4 – 5 3 - 5 4 3 0.5 No Pass


4 – 5 3 - 5 4 3 0.5 No

Pass

Single Jersey(Navy color) 4 – 5 3 - 5 4 3 0.5 No Pass

Shrinkage Achievement

SampleTarget

Length Width

Actual

Length Width

Variation

Length Width

Remarks

Elastane Single Lacoste (Aqua color)

±5% ±5% -6.3% -2% -1.3% No Pass(special case)

Elastane Single Lacoste (Chocolate color)

±5% ±5% -5% -2% No No Pass


±5% ±5% -2.4% -2.9% No No Pass

Single Jersey(Navy color) ±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 control2. Fabric temperature control3. Steamer pressure4. Water and chemical flow5. Liquor pH control6. Conductivity of liquor or fabric7. Specific gravity of process liquor8. Pad pressure and nip expression9. Compensator pressure10. Liquor level11. Fabric speed12. Chemical dosing13. Automatic filling of baths14. Data for steam, water, chemical and electricity consumption15. Process visualisation/schematics16. Automated mangle rinsing17. Automated I R predryer heat control to speed up batch changeover18. Control of oxidation baths19. Control of final fabric pH20. Rapid substitution of operating process details to cope with changes in substrate quality

being processed

Anticipated benefits from investment in control technology

Factor BenefitShade reproducibilityLevelnessMinimal damage of the substrate

Improved quality

RFT dyeingLow liquor ratiosWater recovery and reuse Low-temperature dyeing Controlled equipment

Savings in resources (steam, water, effluent, power)

Consistent dye and chemical weighing and dispensing Reliable recipe calculation

Elimination of errors

Shorter cycle timesLess downtime and less cleaning through schedulingReduced manning levels

Productivity increases

Rationalised/standard productsBetter stock control

Savings in dyes and chemicals

Instrumental colour measurement Improvements in productivity and reproducibility

Control functions for dyeing machine

Function RequirementMachine fill Actuated valve and level sensorRaise to initial temperature at rapid rate of rise

Actuated steam valve and temperature sensor

Circulate material or liquor Controlled electric motor or pumpRaise to top temperature at controlled ramp

Flow reversal sequenceHolding time at top temperatureControlled cooling ramp Actuated valve on cooling waterDrain 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

Factors of major importance Liquor-to-goods ratio Weight of electrolyte (cotton dyeing) Weight of

auxiliary product Time of dyeing pH of dyeing

Factors of minor importance Yarn construction (e.g. twist) Degree of bleaching (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

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

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.

Ecological parameters:

Process Temp. (C) P Time(min) M:L ratioScouring-bleaching

100 10.5 30 1:8

Enzyme wash 5070

5 3010

1:8

Reactive dyeing light

shade

60 10.5 60 1:6

Reactive dyeing med.

to dark shade

60-65 10.5 60 1:6

Turquise color dyeing

70-80 10.5 90 1:6

Polyester stripping

90 4.5 30-45 1:8

Cotton stripping

100 11 30 1:8

Polyester dyeing

130 4.5-5.5 60 1:8

Cotton whitening

100 30 1:6

H

Dyeing parameter

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