PROCESS CAUSTIC SODA RECONCILIATION

Preferential adsorption of caustic soda by cotton fabric

In a controlled study on a batch of 1200 kgs of 2 meters / Kg (desized and scoured) Cotton fabric on a Chain Mercerizer, the following observations were made.

In individual cases, the figures for bath concentration, expression, caustic pick up etc. may differ, but the general methodology of calculations will hold good. This exercise gives an indication of the concentration of feed caustic for maintaining a given impregnation bath concentration.

Material balance

We may take the same example for working out the material balance.

The mercerizing process being predominantly a physical process, theoretically the entire 27kgs caustic present in the 90 litres picked up by fabric needs to be washed off in a controlled fashion not only efficiently but also to ensure an end wash water caustic concentration of 50 to 60 g p l.

The actual caustic on fabric before start of wash was found to be 27.42 %

Monitoring of Caustic pick up

It is desirable to monitor the caustic pick up by the fabric after impregnation frequently at least weekly once. These figures would be helpful in managing the washing operations optimally. As pointed out earlier higher the caustic carried greater is the effort to wash it off. Also, the material balance and dynamics of washing can be understood and controlled only if the caustic percent picked up by fabric is known. We shall look at these aspects under washing operation.

Mercerizing Grey (without De-sizing)

A number of Process Houses resort to grey mercerizing. The attendant consequences are:

1. The fabric is highly non absorbent because of the size and also due to the inherent nature of the cotton that has not been scoured and hence requires wetting agents.
2. The fabric shall require a longer dwell time for caustic penetration, yet not likely to be complete.
3. The size removed during the operation renders the caustic bath highly contaminated and when repeatedly used becomes viscous and slimy.
4. The quality of mercerizing is also affected. The Ba activity number invariably falls short of even 130 against the required figure of 140 +.The mercerizing effect is not likely to be uniform across the fabric width and length. Using such a fabric for dyeing certainly is not recommended.
5. Grey mercerizing is employed for whites by some of the Processors, but it is more from the point of view of ‘apparent considerations of costs and convenience’ and not on quality. More over, where both whites and dyed are mercerized in the same machine, the contaminated caustic shall cause problems on fabrics for dyeing.
6. Where the caustic is to be recovered the sized contaminated caustic shall pose a number of problems in the recovery plant. I.e.. Clogging of the lines, froth, lowering of the heat transfer efficiency, lower capacity utilization etc. The wetting agents added will interfere and cause foaming in the evaporator calandria.

A good Process House with intent on quality shall be more than rewarded in terms of results – i.e.. brilliance of shade / whites, lesser reworking / complaints by avoiding grey mercer sing.

Dwell Time and Stretch

The dwell time for swelling by good absorbent fabric shall be a minimum of 48 to 50 seconds.
The term ‘Stretch’ as already pointed is more to arrest the longitudinal shrinkage of cotton during its swelling in the lateral direction.
The stretch in the warp direction is imparted by the positive pull adjustments provided in the mercerizer machine.

Weft way Stretch

In the case of chainless mercerizer, Weft way stretch is achieved by efficient expanders and also by the dovetail arrangements where the fabric is restrained to slide against the cylinders, thus prevent shrinking weft way. The chainless mercerizer does suffer the relative disadvantage of lower weft way stretch, particularly in very open constructions / low reed x pick qualities. Where the construction is dense and the cover factor is high the problem is less pronounced. In a composite mill it is possible to adjust the grey width a little higher by increasing the width in reed. Where such flexibility is not possible, it may be necessary to mercerize such fabrics in the chain Mercerizer. Alternatively the fabric needs to be stretched in a stenter before mercerizing.

The advantages of a chainless mercerizer are multifold – like more number of super imposed ends, two ends side-by-side etc .The production / productivity is high. The maintenance is relatively less compared to the chain mercerizer where the chains and clips need to be conditioned / replaced frequently. The other advantage is that the fabric is all the time in contact with caustic soda liquor, during the dwell time, unlike in the chain mercerizer where the caustic is mangled out after impregnation. So long the fabric is reasonably absorbent and caustic pick up is sufficient, both the systems are quite satisfactory.

In the Chain Mercerizer the weft way stretch required is physically checked by gradual adjustments of the chain width, while the fabric is moving and the adjustments stopped, when stretch is maximum beyond which the fabric would tear. This setting known as the brake width should be checked and determined for each of the sorts and a table of the brake widths for different sorts should be displayed for day-to-day operational settings. However, every time a sort is changed the brake width needs to be watched even for routine sorts to avoid exceptional cases of fabric width anomalies.

Washing off operation

Washing off operation starts in the stabilizer in the case of chainless mercerizer and in the chain section of the chain mercerizer. The washing is carried out in counter current system as already explained in detail under the two kinds of Mercerizers in the earlier
issue. The wash water supplied to this section is through the recuperator/s. Totally enclosed recuperator/s, sometimes called Matter box form a part of washing zone
immediately after the chains / stabilizer designed to provide the necessary agitation, dwell time and high temperatures to wash off caustic efficiently.

Where water is available in plenty and recovery of caustic soda is not practiced, the elaborate control system for washing is not very critical. At the outset of this article it was mentioned that for pollution abatement considerations and to meet the stringent specifications of statutory rules, the plants have no option to avoid effluent treatment. It is in the interests of the Processor to install and run the caustic recovery plant and avoid expensive treatment costs.

When wash water caustic is to be recovered it would be desirable to understand the material balance of the whole system. Unduly diluted caustic wash water is not economically viable for recovery operation. The wash water should be at least 50 to
60 g p l for an economically viable recovery.

The above requirement poses a condition that the washing system should work efficiently not only to wash off caustic Soda but also discharge consistently 50 to 60 g p l caustic soda in the wash water.

OPERATIONAL DETAILS

The most commonly practiced method of mercerization is feeding the fabric dry to the mercerizer.
We may look at the Mercerizing as a three-fold operation.

      1. Impregnation,
      2. Dwell time and Stretch
      3. Washing off operation in the stretched state.

Each of these operations is important for the satisfactory mercerization. We shall look at the operational details and the possible mistakes that may be committed.

Impregnation:

1. Ambient Temperature

The bath concentration is desired to be maintained at 270 g p l and though the activity is a dry impregnation process, the maintenance of the bath concentration is tricky.

The caustic pick up depends on

• The expression of the impregnation mangle
• The preferential adsorption of the caustic from the bath.
• The variation in the moisture content of the incoming fabric (under drying).
• Over drying of fabric (Affects absorbency / increase temperature of bath)

      Accordingly, the bath concentration will be affected.

2. Hot Impregnation

The phenomenon of swelling starts from the outer most peripheral layer of the fibres that comes in contact with mercerizer strength soda first. As the swelling process continues and fibres in successive layers start swelling progressively, the process of diffusion of caustic to the interior is made more and more difficult. There are chances of incomplete mercerization of the interior fibres

(The above phenomenon is the main cause for the development of hot mercerization techniques as swelling is relatively very low at higher temperatures. Higher temperatures lower the viscosity and density of the caustic soda. Taking advantage of these characteristics and the heat energy available, the diffusion process of caustic into all the interior fibres also, is rendered very effective. However fabric needs to be cooled for swelling to take place, before washing off.)

The intermediate nipping after impregnation facilitates diffusion process by mechanical means to penetrate the interior fibres to the extent possible.
Addition of Non-Cresylic wetting agents also helps in wetting and penetration process.

In the case of Chain Mercerizer the expression plays a major role in pushing the caustic liquor physically into the substrate before swelling starts taking place. There is also intermediate impregnation and nip, half way through the dwell time to further assist the impregnation. ‘Stretch’ is imparted on the chains before washing off.

In the chainless mercerizer the fabric is immersed in the bath all the time and there are also intermediate nips for assisting diffusion mechanically. The fabric is not allowed to shrink and in the stabilizer zone the caustic is washed off in the stretched condition.

However the final caustic carried by the fabric is to be washed off. It is the strength of the impregnation bath in g p l that is important for swelling. At the same time the caustic carried by fabric should be minimum in order to reduce the washing load.
Feed Concentration / Adverse factors that influence impregnation

As it is a dry pad system the problem of exchange phenomenon does not arise unlike in the wet on wet process. However, preferential adsorption of caustic soda by the fabric will dilute the bath, if feed caustic strength is not higher. At the mercerizer strength of 270 g p l the preferential adsorption is of the order of 3% and the feed caustic need to be around 30 g p l more than the bath concentration. (In terms of ºTw it would be 48 ºTw. Bath and 52 ºTw. Feed – provided the bath and feed are both fresh and clean.). The safe bet would be to estimate by titration in terms of grams/liter of pure caustic (atmospheric CO2 contamination and colloidal and suspended solids particularly while using recovered caustic could vitiate sp.gr. figures).

The general arrangement to effectively handle this phenomenon and also to even out small variation in moisture content in the incoming fabric, the impregnation tank is connected to a large over head feed tank and the liquor in the impregnation bath is circulated constantly by a closed circuit connection to the feed tank through a pump. The feed tank concentration is continuously monitored and adjusted by strong liquor / recovered caustic from the Caustic Recovery Plant and the feeding is done by gravity flow.

To overcome the over dry situations, moisture control devices may be helpful at the stage of drying. Majority of the process houses carry out cylinder drying and these dryers are not provided with such instrumentations. The minimum safe guard activity would be to cool / condition the fabric overnight and or provide a cooling conditioning zone in the entry side of the mercerizer.

Small variations in the drying may be taken care of by the adjustments to the feed liquor; but too much fluctuation in the moisture content and or feeding of very hot over dried fabric should be avoided. Over dried hot fabric will also increase the bath temperatures,

Coming back to the impregnation liquor, it is desirable to maintain the bath at a steady temperature as low as possible – (around 30º C to 35º C at the most). The making up process of the feed liquor will tend to raise the temperature. It is necessary to provide closed circuit cooling by heat exchanger with cold water and also on line for cooling recovered caustic from the Caustic Recovery Plant

High variations in bath concentration, temperature, moisture content in the fabric and over dried hot fabric can contribute to variations in the quality of mercerization.

The impurities in the impregnation liquor could be both suspended solids and dissolved solids other than Caustic Soda –i.e. Sodium Carbonate. The suspended solids over a period of time will accumulate and affect the flow and also the expression characteristics. Suspended solids problem can be overcome by providing filters at strategic places. Even with the best of filters, the colloidal suspensions cannot be effectively eliminated and as pointed out earlier, density measurements would be faulty. Mercerization in grey state, particularly heavy fabrics with size would pose such problems in a greater measure.

The dissolved carbonate of sodium will contribute to the apparent ‘strength’ of bath caustic soda. The method of titration should provide for finding the Caustic Soda strength and not the total alkalinity. The carbonate is constantly formed by the exposure of caustic soda to the atmospheric Carbon-di-Oxide. The chances of contamination of Sodium carbonate are more in case of using recovered caustic over and over again.

Storage of strong caustic liquors should be ensured in closed containers / kiers. Transportation of hot wash liquors to storage, to and from the caustic recovery plant etc. should be through pipelines, not through open channels.

The scum accumulating on the top in the impregnation bath should be constantly cleared.

CHAIN AND CHAINLESS MERCERIZERS

There are different types of arrangements employed depending on the machinery selection

Chain Mercerizer

In the chain mercerizer there are arrangements to impregnate — nip — give partial dwell time — again impregnate — nip — give the balance dwell time — give a final nip before entering the chain and washing off zone. The intermediate impregnation and dwell arrangement is practiced where higher production speeds are required. However the total dwell time is the same – (minimum 48 / 50 seconds.).
Timing drums (blank cylinders) immediately after the nips are arranged very close to each other such that the fabric as it leaves one cylinder dove tails on to the second one giving resistance to sliding and preventing the fabric to shrink weft way and also avoid curling of the selvedges. Warp way stretch is achieved by the positive forward pull by the following nip / system. The timing drums also provide the necessary dwell time. The number of cylinders will depend on the dwell time and the speed. The fabric is ‘stretched’ in the stenter zone to reach its maximum width before washing off, without tear / damage to the fabric. The washing off is carried out in this zone in the stretched condition by counter current flow of hot water. Arrangement of Weirs and Suction units to repeatedly spray in a cascade and suck out the wash water through the fabric on the move facilitate efficient and thorough washing.

Chainless Mercerizer

In the chainless mercerizer, the fabric is passed through a set of very efficient expanders and fed continuously on to cylinders arranged in two rows bottom and top. The bottom set is soaked in the impregnation bath. The principle of arresting / restricting weft way shrinkage is achieved by the dove tailing arrangement. The cylinders are positively driven unlike in chain mercerizer where the cylinders are free mounted. There may be intermediate nips to assist penetration and a final heavy nip before entering the stabilizer / washing off zone. The number of cylinders in each of the top and bottom rows will depend on the rated speed of the machine and the dwell time. The arrangement of cylinders in the stabilizer / washing off zone is also similar to the impregnation zone and the fabric is washed in a counter current flow from the recuperator. In both the zones there are also independent close circuit circulation of liquor within their respective baths
with arrangements to spray the liquor through perforated pipes on the upper cylinders section. They are arranged such that the liquor spray does not fall directly on the moving fabric.

Chain cum Chainless Mercerizer

The advantages of both chain and chainless Mercerizers are exploited.
The relative merits and de-merits / problems of chain and chainless Mercerizers will be discussed later.

 A SCHEMATIC VIEW OF THE MERCERIZATION FLOW CHART

MERCERIZATION AND POLLUTION

Caustic soda is a strong alkali and the mercerizer wash liquor effluent can carry over 20 to 25 kgs of caustic Soda for every 100 Kgs mercerized. Such levels of un-fixed caustic soda shall be harmful to the environment.

The process of mercerization is mostly a physical phenomenon and theoretically the bulk of caustic used is possible to be recovered. The preferentially adsorbed caustic is difficult to be washed off fully economically and hence only a small portion of this caustic need to be neutralized and removed. The balance bulk can be recovered and concentrated to mercerizer strength caustic and re-used. The recovery efficiency could be well over 90%. As a thumb rule the cost of recovery is roughly 50% of the price of fresh caustic. We shall discuss this aspect later.

However quite a number of Process Houses do not recover the caustic. The general practice is to partially use the washed water caustic soda in the preparatory scouring process and drain the bulk balance. There are also attempts to sell the wash liquor to Hypo- chlorite manufacturers. The caustic soda in the wash liquor is very large and is a pollutant that needs to be neutralized and treated. The resultant Sodium salt generated will cause increase in ‘per Sodium levels’ in the effluent beyond permissible limits and removal of dissolved salts is cumbersome and expensive requiring Reverse Osmosis / Molecular Sieve filtration kind of treatments even to drain on own land. With salt intensive Reactive dyeing processes coming to stay, the salt concentration in the effluent can go out of control, not to speak of other pollution loads including color. Treatment of effluent is a primary requirement committed to social responsibility and should be dealt with voluntarily. Any attempt to consciously avoid generation of pollutants would not only help the cause of this responsibility but also contribute to lesser treatment costs.

A majority of small Process Houses does not put up CRP plants because the quantity of wash liquor generated is not sufficient to economically install and run a recovery plant.
With the statutory requirements of stringent implementation of pollution control norms and threat of closure of plants for non-compliance, there can be no escape but to conform to the norms specified. We shall discuss the various issues as we proceed.

MERCERIZING

. Certain classes of colors / some colors of the same class do not render themselves suitable for application on un- mercerized cotton substrates, particularly coverage of immature / dead cotton. Therefore the choice of colors for application becomes limited. Still majority of circular knitted hosiery is not mercerized; the reason is not that it is not required, but the attendant difficulties restrict the processors to find other methods to achieve results – a compromise that cannot substitute mercerization. Technology to mercerize in tubular form and the advanced machineries developed in recent times have made it feasible to extend mercerization to tubular knitwear.

Mercerization -Theory and Practice

Application of Caustic Soda swells cotton. Whereas a higher concentration of caustic soda is required at higher temperatures, same level of swelling is obtainable with lower concentrations at lower temperatures. When stretch forces are applied to counter the swelling and the caustic is washed off in the stretched condition the cotton retains the new dimensions. John Mercer was the first to observe the phenomenon of swelling in strong caustic soda and extensive work on this process by later workers led to what has come to stay as mercerization.

The term stretch here should be understood as the stretch force applied to offset the normal shrinking process during swelling to the extent possible without rupture to the matured fibres.

The optimal profiles of Concentration, Temperature and Time were determined as 50° Tw (Sp.Gr. 1.25 – 300 grams/liter), 17deg C and 50 seconds respectively

Swollen fibre tends to become cylindrical in shape and the lumen or the central cavity tend to get reduced in size. Due to stretch de -convolution of the cotton fibre is also facilitated – these two physical changes enable efficient and even reflection of incident light, thus improving luster and brilliance. Also much of the crystalline regions are converted to amorphous state and therefore, cotton becomes more permeable providing easy and freer access for various dyes and chemical solutions to diffuse /penetrate in to the substrate. The strength also improves considerably.

The immature cotton gets ruptured due to swelling and along with the dead cotton gets dissolved in the mercerizer strength caustic Soda.

Over the years on the basis of cost benefit considerations the approach to mercerization concentration/temperature profiles have undergone changes but the principle of swelling and stretch has remained the same

Mercerization Temperature

Considering the cost of cooling to 17° C (refrigeration) with only marginal advantages in swelling, mercerization nowadays is carried out at ambient temperatures The dwell time has not under gone any change and remains at around one min (50 Seconds.) that is the minimum.

Concentration:

There have been a number of views put forward by Processors that the desired swelling and dissolution of immature / dead cotton are achieved even at lower concentrations and for very dark shades the reflected light does not contribute much to the luster and therefore lower concentrations of caustic soda would suffice. Causticizing at 12% to 18% strength is still being practiced. Therefore strengths in the mercerizer impregnation bath are being maintained at lower levels.

This tendency should be avoided to prevent any complacency and ending up with inadequate mercerization. With due respects to these views we shall proceed further.

The more important aspect is that the mercerizer bath concentration need to be maintained consistently to avoid variation in dyeing/finishing deficiencies.
The impregnation bath concentration has been generally established at 270 g p l (48 ºTw) of Caustic Soda.

The density measurements to control the bath strength with hydrometers in º Tw or º Be.. is widely practiced but such measurements are likely to mislead the correct concentration of the caustic soda, as the bath would progressively bet contaminated with leached out impurities from the fabric undergoing mercerization and that would also contribute to density figures.

DEMINERALIZATION:

DESIZING:

WETTING AGENTS:

SCOURING AGENTS:

MERCERISING AGENTS:

DYE-BATH CONDITIONERS:

SEQUESTERING/DISPERSING/SOAPING AGENTS:

SOAPING AGENTS:

STAIN REMOVERS:

HYDROGEN PEROXIDE STABILIZERS:

CATIONIC DYE FIXING AGENTS:

CATIONIC FORMALDEHYDE FREE DYE FIXING AGENTS:

FINISHING AIDS:

NON-IONIC SOFTNERS

CATIONIC SOFTNERS

ANIONIC SOFTENERS

SILICONE SOFTNERS

LUBRICATING AGENTS

Introduction

I will be using Textile ID Stains, and multi fiber fabric from Testfabrics, Inc. In my experiment I will use TIS #1, #3A, and #4, along with mulitfiber fabric #43. In the stain test, the stains will act as the variable, while the fibers are constant. In the burn test the fibers will act as the variable.

Background

There are many different types of fibers, created and used with many different purposes. All fibers can be put into two main categories, natural and synthetic. This will be one of the categories I use to define my unknown samples. TIS #3A, and #4 are best to identify synthetic fibers; #1 is best for natural fibers. Before and after I stain the fibers I will use the colorimeter to test the L*a*b* coordinates of the color. The L* corresponds to the lightness of the color, the a* with the red/green attributes, and the b* with the yellow/blue attributes. This will allow me to get an exact color of the fabrics, and then be able to compare how the known fibers reacted to the dyes, as well as the unknown fibers.

Procedure

Burn Tests

Supplies

• Fiber samples: cotton, silk, wool, polyester, rayon
• Six unknown fiber samples
• Matches
• Aluminum foil

1. Obtain a sample of cotton.
2. Hold sample with tweezers, light on fire with a match.
3. Drop onto aluminum foil.

Repeat with each different fabric sample.

Stain

Supplies

• Multi-fiber Fabric #43
• Unknown multi-fiber strip
• 6 beakers
• Hot Plate
• 0.1% solution of each stain
• 10% acetic acid
• Thermometer
• Stirring Rod
• Non-optical detergent

Stain #1

1. Weigh material to be tested, let it be “x” grams.
2. Use enough tap water to cover specimen to be tested. Bring water to rapid boil
3. Add 2(x) cc of 0.1% solution of stain #1 solution and continue to boil for 5 minutes.
4. Add sample to be tested, stir and boil for 5 minutes
5. Rinse until clear, dry.

Stain #3A

1. Weigh material to be tested, let it be “y” grams.
2. Use enough tap water to cover specimen to be tested, bring to boil
3. Add 0.03(y) cc of 0.1% solution of stain #3A; bring it to a rapid boil
4. Add “y” cc of 10% acetic acid, boil for an additional 5 minutes.
5. Add sample to be tested and continue boiling and stirring for 5 minutes
6. Rinse in hot water.
7. Soap in non-optical detergent at 120F for 5 minutes

Stain #4

1. Weigh material to be tested, let it be “y” grams.
2. Use enough tap water to cover specimen to be tested, bring to boil.
3. Add 0.03(y) cc of 0.1% solution of stain #3A; bring it to a rapid boil
4. Add “y” cc of 10% acetic acid, boil and additional 5 minutes.
5. Add sample to be tested and continue boiling and stirring for 5 minutes..
6. Rinse in hot water
7. Soap in non-optical detergent at 120F for 5 minutes

Microscope

1. Remove individual fibers from the strip.
2. Place on microscope slide.
3. Tape cover slide onto slide.
4. Place in microscope and focus.
5. Place the lens of the camera onto the eyepiece to take picture.

Observations and Data

Burn Test

Stain Test

Stained Multi-fiber strips

Labeled Unstained

Unstained	#1	#3A	#4

L*a*b* results

Unstained Fibers

Stain #1

Stain #3A

Stain #4

Microscope Pictures

Unknown Strip

Burn Test

Stain Test

Stained Multi-fiber strips

L*a*b* Results

Unstained Fibers

Stain #1

Stain #3A

Stain #4

Microscope Pictures

Conclusions

After analyzing the burn tests, stain tests and the microscope pictures, I have been able to label the unknown fibers as follows:

The known multifiber strip included fibers other than those that I focused on in my tests. Using the stain test results I was able to use these other fibers in identifying the unknown samples.

If I could do more with this project I would go back and do further tests on the fibers I have predicted to be one of the unknowns, but did not focus on in my project, such as acrylic, nylon and spun diacetate. I would also test other fibers to try and identify the still unknown, #3.

Links

Testfabrics, Inc

Acknowledgements

Dr. Bordley

Dr. Bachman

Miranda Klaas of Testfabrics, Inc.

Courtesy:Elizabeth Garfield

Given below may be the best route for processing a knit poly-cot blend:

Pretreatment:

1. Wetting off:

Recipe:

Wetting agent (No foaming) = 0.5%

Treat @ 70°C for 10 minutes.

Drain.

2. Scouring & Bleaching:

a. Recipe:

i. Soda Ash = 0.5%

ii. Caustic Soda = 0.7%

iii. Non foaming detergent = 0.5%

iv. Peroxide Stabilizer = 0.5%

v. Hydrogen Peroxide(50%) = 1.5%

1. @ 85°C for 1 hour.

2. Drain and do cold wash

3. Neutralization:

a. Recipe:

i. Acetic Acid = 1 ml/liter

1. Treat @ cold for 10 minutes.

2. Wash cold 10 minutes

3. Check pH and let it be 6

4. Heat Setting:

a. Do heat-setting in a stenter @ 200°C for 30 seconds (split open) with 3% overfeed on pins at 15 meters/minute speed.

5. Mercerising:

a. Recipe:

i. Caustic lye = 50°TW

ii. Permenol N = 10 ml/liter (Mercerizing Wetting Agent)

Wash free from residual alkali

6. Polyester Dyeing: (Optional)

a. Recipe:

i. Lyogen PESI = 1.0 g/l (Dispersing & Leveling Agent)

ii. Acetic Acid = 1.0 g/l

1. Run @ 50°C for 10 minutes

iii. Add dissolved dyestuff @ 50°C and run 10 minutes

iv. Raise the temperature from 50 to 115°C @ 2°/minute – 30 minutes

v. Raise the temperature from 115 to 135°C @ 0.5°C/minute – 40 minutes

vi. Cool to 80°C and drain

7. Reduction Clearing (R.C.):

a. Recipe:

i. Cyclanon ECO = 2 grams/liter (Reduction Clearing Agent from BASF)

ii. Acetic Acid = 2 grams/liter

1. Treat at 80°C for 10 minutes

2. Wash cold

8. Reactive Dyeing:

a. Set pH to 6 by addition adequate quantity of Acetic acid ( may be up to 0.3 to 0.5 cc/liter)

b. Cotfix Turq Blue H2GP = 3.0%

c. Cotfix Yellow ME4GL = 1.0%

d. Glauber’s Salt = 80 grams/liter OR

e. Soda Ash = 20 grams/liter

i. Dye using Special Turquoise Blue Dyeing Method

a. Cotfix Turq Blue H2GP = 3.0%

b. Cotfix Yellow ME4GL = 1.0%

c. Glauber’s salt = 80 grams/liter

d. Soda Ash = 10 grams/liter

e. Caustic Soda Flakes = 2.75 grams/liter

Dye using the Special Turquoise Blue Preconditioning Method:

9. Neutralize:

Acetic Acid 2.5 grams/liter (instead of 1 g/l)

10. Soaping:

a. Method -1:

I – Soaping:

Recipe:

Lissopol D paste 2 grams/liter @ 80°C for 20 minutes.

II – Soaping:

Recipe:

Lissopol D paste 1 gram/liter @ 80°C for 20 minutes.

b. Method – 2:

I – Soaping:

Recipe:

Sandopon RSK Liq 2 grams/liter

Lyocol RDN 1 gram/liter (dispersing agent for Disperse dyes – used here for better soaping)

@ 80°C for 20 minutes.

II – Soaping:

Recipe:

Sandopon RSK Liq 1 gram/liter

Lyocol RDN 0.5 gram/liter

@ 80°C for 20 minutes.

c. Method- 3:

I – Soaping:

Recipe:

Cyclanon X-CW NEW = 2 gram/liter

Lyocol RDN = 1 gram/liter

@ 80°C for 20 minutes.

II – Soaping:

Recipe:

Cyclanon X-CW NEW = 1 gram/liter

Lyocol RDN = 0.5 gram/liter

@ 80°C for 20 minutes

Hot Wash

Cold Wash

11. Acetic Acid treatment:

Acetic Acid 0.5 cc/liter

12. If necessary use Formaldehyde free Cationic fixing treatment.

a. Sapamine OC = 1%

b. Cationic Fixing = 1%

i. @ Cold treat for 30 minutes.

ii. Wash cold

iii. Drain & unload the batch.

Note:

If a dose of 0.3 cc/liter of Acetic acid is incorporated in the soaping bath, the staining of reactive dyes on polyester during soaping may be completely avoided. Soaping bath pH should be 5 to 6.

A final wash after Soaping with 1 gram/liter of Acetic Acid or 0.5 gram/liter of Formic acid and maintaining a pH 5 to6 during drying would avoid tinting of reactive dyes by migration in to polyester.

Even after taking all precautions, if the polyester part still gets stained, treat the tinted fabric with:

Acetic Acid = 2grams/liter

Alcosperse AD = 2 grams/liter

Cibapon R liq = 2 grams/liter

At 80°C for 30 minutes; this would remove the stains from the polyester.

Summary:

1. In preparation no residual chemicals of the pretreatment should remain on the fabric. The RFD fabric should be checked for a pH of 6 at the end of pretreatment and before dyeing.

2. The pH should be 6 at the beginning of reactive dyeing.

3. After dyeing is over, neutralization with Acetic acid should be done and check the pH to 6.

4. Ensure sufficient hot wash to reduce the electrolyte (salt) concentration to a minimum of 1 g/l before soaping, otherwise imperfect soaping would be done.

5. During soaping maintain a pH of 6 to avoid staining of polyester.

6. The soaping temperature should be maintained strictly at 80°C. More than this would open the polyester fiber and create a tendency for unfixed reactive dye to enter into polyester fiber as stain.

7. The final pH should be 6 before drying and it may be controlled by using 0.5 cc/liter of Formic Acid.

Notes on Resin finishing:

Recipe:

Resin KVS = 45 g/liter

PV Acetate = 25 g/liter

PVA = 25 g/liter

PE = 20 g/liter

Acetic Acid = 1 cc/liter

Pad 2 dip 2 nip – pressure 35 kgs/sqcm. – speed 25 mtrs/minute and temperature – 170°C – No over feed.

• Start Dyeing @50°C; ensure the starting bath pH be 6; adjust with Acetic Acid if necessary.
• Add salt (vacuum or Glauber’s salt) and hold for 15 minutes
• Add ½ the volume of dissolved and filtered dyestuff and hold 10 minutes.
• Add ½ the volume of dissolved and filtered dyestuff and hold 10 minutes.
• Raise the temperature @2°C/minute to 80°C and hold for 20 minutes.
• Add ½ alkali (Soda ash) and hold 25 minutes.
• Add ½ alkali (Soda ash) and hold for 30 minutes.
• Check sample
• Drain
• Cold wash (10 + 10 minutes)
• Neutralize @ 40°C with adequate qty of Acetic acid.
• Cold wash – 10 minutes
• Hot Wash @ 70°C (2°C/minute) – 10 minutes
• Soap @ 95°C – 15 minutes (1^st soap)
• Soap @ 95°C – 15 minutes (2^nd soap)
• Soap @ 95°C – 15 minutes (3^rd soap)
• Hot Wash
• Sample check for shade and wash fastness
• Cold wash (10 + 10) minutes
• Acid wash with 1 gpl of acetic acid
• In the same acid bath – cationic softener treatment – 20 minutes
• Check pH – 6
• Unload.