Reactive Continuous Dyeing

Textile Chemicals

Drimaren® HF/CL reactive dyesPad Batch and Continuous Dyeing procedures

Textile Chemicals


Table of contents

1. Introduction 3

2. Pad Batch process 3

2.1 Introduction 3

2.2 Process principle 3

2.3 Operating procedure 3

2.3.1 Fabric requirements 3

2.3.1.1 Sewing together the pieces 4

2.3.2 Preparation of the pad liquor 4

2.3.2.1 Dissolving the dyes 4

2.3.2.2 The alkali liquor 4

2.3.3 Alkali systems 4

2.3.3.1 Fixation with sodium silicate and caustic soda 4

2.3.3.2 Fixation with soda ash and caustic soda 5

2.3.4 Pad liquor stability 5

2.3.5 Padding 6

2.3.6 Fixation by batching 6

2.3.7 Washing off 7

2.4 Rapid fixation (lab technique) 7

2.4.1 Rapid fixation in a microwave oven 7

2.4.2 Rapid fixation in a drying cabinet 8

2.4.3 Examples 8

2.5 Clariant tailing test 8

2.6 Shade change during drying 9

3. Pad Dry Chemical Pad Steam process 9

3.1 Introduction 9





3.3.2 Preparation of the dye pad liquor 10


3.3.2.2 Pad liquor stability 10

3.3.3 Padding 10

3.3.4 Intermediate drying 10

3.3.4.1 Explanation of migration 11

3.3.4.1.1 Clariant migration test 11

3.3.5 Preparation of the chemical pad liquor 11

3.3.6 Padding 11

3.3.7 Fixation by steaming 12

3.3.8 Washing off 12


4. Pad Wet Steam process 12

4.1 Introduction 12







4.3.2.2 The alkali liquor 13

4.3.2.2.1 Working without a metering pump 13


4.3.3.1 Pad liquor stability with a metering pump 14

4.3.3.2 Pad liquor stability without a metering pump 14

4.3.4 Padding 14




5. Pad Thermofix process 15

5.1 Introduction 15






5.3.2.1 Influence of the urea 16

5.3.3 Dissolving the dyes 16

5.3.4 The alkali liquor 16

5.3.4.1 Working without a metering pump 16


5.3.5.1 Pad liquor stability with a metering pump 16

5.3.5.2 Pad liquor stability without a metering pump 16

5.3.6 Padding 16


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5.3.8 Fixation in hot air 16



6. Pad Moist process 17

6.1. Introduction 17




6.3.2 Sewing together the pieces 18

6.3.3 Preparing the dyestuff pad liquor 18

6.3.4 Dissolving the dyestuffs 18

6.3.5 The alkali liquor 18


6.3.7 Padding 18

6.3.8 Drying/Fixation 18



7. SWIFT process for dyeing PES/CEL blends 19

7.1 Introduction 19





7.3.2 Preparation of dye pad liquor 20


7.3.2.2 Pad liquor stability 20

7.3.3 Padding 20


7.3.5 Thermosoling 21

7.3.6 Preparation of the chemical pad liquor 21

7.3.7 Padding 21




8. Dye selection 21

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1. Introduction

In continuous dyeing processes, the substrate is treated far more

gently than in exhaust processes, i.e. on jets or in package dyeing

machines. For large batches continuous processes are often far

more economical. Most of the Drimaren® HF and CL dyes are

suitable for the continuous processes described in this shade card.

2. Pad Batch process

2.1 Introduction

The pad batch process is a semi-continuous dyeing method which

is extremely interesting from the point of view of both the machinery

and the application technique. The only machines required are a

padder, batching device and washing off equipment.

In view of the steadily increasing cost consciousness in the textile

processing industry, this economical, time and energy-saving

process is of considerable importance.

This shade card contains detailed information in the text section

about the technique of this process which will ensure its reliable

application in the dyehouse.

The pad batch process offers the following decisive advantages:

■ Simple working method ■ Short setting up and machine down time ■ Low machine and energy cost ■ High color build-up ■ Good penetration even with tightly structured goods ■ Economic process

2.2 Process principle

The principle of the pad batch process is to pad the goods at room

temperature with a dye solution which also contains the necessary

alkali for fixation and any other chemicals. The fabric is rolled up on

a beam and wrapped in plastic film ready for the fixation step. Dye

fixation takes place during batching at room temperature. Slow

rotation of the fabric batch is necessary during batching to avoid

unlevelness and drainage of the dye liquor.

The fabric is batched for the required fixation time before the

unfixed dye is removed from the fibers by rinsing then soaping at

the boil. This washing off treatment is essential to obtain the

optimum wet fastness properties and final shade.

2.3 Operating procedure

Various factors, which are important for a reliable process flow, are

described in the following sections:

■ The prepared state of the material to be dyed ■ Preparation of the pad liquor ■ Padding ■ Fixation by batching ■ The washing off process

2.3.1 Fabric requirements

Optimum, uniform pre-treatment of the substrate is one of the most

important fundamentals for obtaining perfect dyeing results with

regard to levelness and appearance of the fabric, etc.

BatchingDyepad liquor

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The pre-treated fabric should fulfill the following criteria for perfect results:

■ Uniform moisture content, very good absorbency (prevent over

drying) and crease free ■ Neutral pH (6-7) and uniform degree of whiteness (important for

pale shades) ■ Free from size, bleaching chemicals, earth metals and salts ■ Cooled to ambient temperature

Regenerated cellulose fibers can be pre-causticized to improve

color yield and significantly reduce their tendency to fibrillate

under mechanical stress.

2.3.1.1 Sewing together the pieces

In order to avoid seam impressions during batching the pieces

should be sewn with a butted seam. The sewing yarn should be of

the same substrate, i.e. cotton or viscose and have received the

same pre-treatment.

2.3.2 Preparation of the pad liquor

2.3.2.1 Dissolving the dyes

When dissolving the dyes it should be considered that there are

different commercial forms. Some products are specially

designated as Cold Dissolving Granules (CDG).

There is a fundamental difference between granules (which include

the CDG formulation) and powder. Some products are specially

designated as Cold Dissolving Granules.

Granules should never be pasted but sprinkled into water. For the

CDG form the water can be cold (20–30 °C). For other forms it is

better to use water at 60–80 °C. This is also true for the powder

products. Mixtures of different commercial forms should always be

dissolved at higher temperature (> 60 °C) by sprinkling them into water.

Before adding dissolved dyes to the feed tank the dye liquor should

be passed through a filter to ensure that any non-dissolved dye or

contamination is held back. Unlevelness and/or spots and possible

damage to the pumps can be avoided in this way.

Cold water should then be used to adjust the dye liquor to the

required volume.

2.3.2.2 The alkali liquor

The alkali required for fixation is pre-dissolved then added, cold, to

the feed tank. The liquor volume is then adjusted as required with

cold water.

2.3.3 Alkali systems

Drimaren® HF and Drimaren® CL dyes can be applied using different

alkali systems: ■ Fixation with sodium silicate/caustic soda ■ Fixation with soda ash/caustic soda

2.3.3.1 Fixation with sodium silicate and caustic soda

Standard recipe:x g/l Drimaren® HF/CL dye

0.5–3 g/l Leonil® EHC liq c

0.5–3 g/l Ladiquest® 2005 liq c

y g/l Caustic soda 36 °Bè

50 ml/l Sodium silicate 38 °Bè

Drimaren® HF/CL dye g/l 0–5 5–10 10–20 20–30 30–40

Sodium silicate 38 °Bè m/l 50 50 50 50 50

Caustic soda 36 °Bè ml/l 8.0 10.0 12.0 15.0 17.0


Sodium silicate 38 °Bè m /l 50 50 50 50 50


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Characteristics: ■ Rapid fixation ■ High operational reliability ■ High pad liquor stability ■ Stable pH value ■ The influence of CO2 (carbonation) and other acid components in

the air are excluded

The caustic soda is added to the bath first, before the sodium

silicate. Sodium silicate can form precipitations with hardness

forming salts which are later deposited on the material and

machine parts. The alkali liquor should be prepared using soft

water or hard water should be corrected by adding a sequestering

agent such as 0.5-3 g/l Ladiquest® 2005 liq c.

When the operating temperature is >30 °C, or high concentrations

of dyestuff are used, the bath stability can be improved by

increasing the amount of sodium silicate to between 70 and 100

ml/l.

2.3.3.2 Fixation with soda ash and caustic soda

A combination of caustic soda and soda ash can be used when the

padding and fixation temperatures are between 20–25 °C.

Standard recipe: x g/l Drimaren® HF/CL dye



10–20 g/l Soda ash

y ml/l Caustic soda 36 °Bè


Soda ash g/l 10 10 20 20 20



Soda ash g/l 20 20 20 20 20


Characteristics: ■ Rapid fixation ■ Easy washing off ■ No influence on fabric handle

2.3.4 Pad liquor stability

The separately prepared dye and alkali solutions are cooled to the

required pad liquor temperature and sent to the padder via a mixing

device. A mixture ratio of 4 parts dye solution and auxiliaries to 1

part alkali solution has provided good results in practice. Other

mixture ratios are also possible.

After mixing with alkali the dye becomes reactive. To ensure

optimum pad liquor stability, i.e. to avoid premature dye hydrolysis,

it is essential to use a mixing device. Where possible the padding

temperature should be 25 °C +/– 3 °C.

All reactive dyes are subject to hydrolysis in the presence of alkali

in the pad liquor. It depends on the time, amount of dye and

temperature. Hydrolyzed dye cannot react with the cellulose. If dye

hydrolysis already takes place in the pad liquor or in the padding

trough there is a danger of tailing. Exact knowledge of the pad

liquor stability of the Drimaren® HF/CL dyes is therefore important.

Details of individual dyes can be found in the shade card inserts or

calculated exactly using the HYDREC program.

The highest pad liquor stability is achieved with the caustic soda/

sodium silicate formula. It decreases with increasing dye

concentration i.e. the rate of hydrolysis increases. This can be

explained by the buffer capacity of this system whose optimum

efficiency is in the low dye concentration region and decreases

with increasing dye and alkali concentration. The bath stability can

be improved, when the padding and fixation temperature is > 30 °C

or high concentrations of dye are used, by increasing the amount of

sodium silicate to between 70 and 100 ml/l. This may impair the

washing off properties depending on the fabric construction and

washing off equipment adopted.

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The HYDREC calculation program gives information on the bath

stability and fixation times, taking into consideration the existing

conditions (temperature, bath volume, running speed, weight of the

goods and liquor pick-up).

The HYDREC program can calculate the required amounts of caustic

soda and sodium silicate necessary by taking into consideration

the different grades (°Bè) used in the industry.

2.3.5 Padding

Padding is carried out on a two or three roller padder, preferably

with an economizing trough (low liquor volume).

Pick-up:60–80 % For cotton woven goods

80–20 % For cotton knit goods

70–90 % For regenerated cellulose

The immersion time, i.e. the time the fabric remains in the pad

liquor before squeezing, is 1–2 seconds. The pad liquor turnover

time should be as fast as possible, i.e. < 5 min to maintain stability

and reduce the risk of tailing.

Pad liquor turnover time is calculated with the following formula:

V = trough volume in liters

g = weight of the goods in grams per running meter

f = dry pick-up in %

v = speed of the goods in m/min.

2.3.6 Fixation by batching

The padded goods are rolled onto a beam, finishing with the

padded end cloth and wrapped in plastic film to avoid premature

drying. The beam is then batched for 6–24 hours while rotating

slowly.

Dye-fiber reaction takes place during batching. For this process the

following points should be considered: ■ The goods must be rolled up with straight edges under constant

tension ■ The padding and batching temperatures should be identical

(+/-3 °C) ■ During batching, the fabric heats up due to the exothermic

reaction. If the batching (surrounding) temperature is higher

than the padding temperature, condensation may form under the

plastic film causing water spotting. Water spotting can be

prevented by covering the fabric batch in a layer of leader cloth,

before it is wrapped in plastic film. ■ If the batching (surrounding) temperature is lower than the

padding temperature, the rate of fixation will slow down,

especially at the edges of the beam. This can be the reason for

poor shade reproducibility, listing and tailing problems. It is

particularly problematic at temperatures < 20 °C.

The fixation times depend on the reaction speed of the individual

dyes, which depends on: ■ The amount of dye ■ The padding temperature ■ The batching temperature ■ The alkali system

Drimaren® Yellow CL-2R, Drimaren® Green HF-5BL, Drimaren®

Turquoise CL-B and Drimaren® Turquoise K-2B require a minimum

fixation time of 24 hours, depending on the depth of shade, to

achieve full fixation. The alkali amounts given for Drimaren® HF and

Drimaren® CL dyes can be used for Drimaren® Turquoise K-2B.

V · 105

g · f · v= Pad liquor turnover time in minutes

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2.3.7 Washing off

Optimum fastness properties can only be achieved on perfectly

washed off material. If sodium silicate has been applied, soft water

should be used for the first few rinsing baths, beginning with cold

water. This prevents deposits of insoluble salts on the machines

and the goods.

Depending on the machinery available, washing off can be carried

out on ■ Open width washers ■ Rope washers ■ Beam washers ■ Any other suitable machine

Soaping is carried out with an addition of Ladiquest® 2005 liq c or

Ladipur® RSK/R3C liq as follows:

Discontinuous methodAfter warm rinsing adjust the fabric pH to 6–7. Care should be taken

to ensure that the fabric has a neutral pH before soaping at the boil.

0.5–3 g/l Ladiquest® 2005 liq c or Ladipur® RSK/R3C liq is added to

the soaping bath and the fabric treated at the boil for 10–20 min.

This is followed by warm then cold rinsing.

Continuous method (example)

Continous washing range with 8 compartments:

1. Overflow rinse at room temperature


3. Wash at 70 °C

4. Wash at 95 °C with 1–3 g/l Ladipur® RSK liq


6. Wash at 95 °C

7. Wash at 70 °C

8. Neutralize at 40–60 °C to pH 6–7 with Sirrix® NE liq

Due to the high alkaline stability of Drimaren® HF dyes, it isn’t

necessary to neutralize the fabric before washing off at high

temperature (80–95 °C) in a continuous washing range. The

material should have a neutral pH ready for drying.

The dye-fiber bond of certain elements from the Drimaren® CL

range can be sensitive to washing off at high temperature under

high alkaline conditions. It is therefore necessary to neutralized (pH

6–7) the fabric before the high temperature washing off step.

2.4 Rapid fixation (lab technique)

Shade matching can be carried out in the lab quickly and with a

high degree of precision. There are two possible methods:

2.4.1 Rapid fixation in a microwave oven

A microwave oven can be used for rapid checking of pad liquors in

the dyehouse. It requires a nonmetallic container with a lid, which

is partially filled with water to imitate ideal fixation conditions and

avoid drying out of the fabric.

Working method ■ Commercial microwave oven, at least 600W capacity ■ Prepare dye and alkali solutions separately ■ Fill a plastic container with 2–3 cm water and place in the

microwave. Set the time to 15 min, 80% capacity (500W). Switch

on the oven without a sample, but with the container to condition

the surroundings ■ Prepare the fabric sample, 9x13 cm ■ Pad at 3 m/min ■ The pick-up should correspond to that in practice (2 immersions

have proved advantageous)

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■ Place the padded sample in a polyethylene bag or wrap in plastic

film (to prevent drying) and dwell for at least 15 min at room

temperature ■ Hang the sample in the preheated fixation box (without bag) and

switch the oven on

After fixation the samples are rinsed and soaped in the usual manner.

The values given are guide values. Depending on the oven and

weight of the material different fixation times may be necessary

(usually between 3–5 min).

It is advisable to compare the shade found using a microwave

against that obtained by standard batching conditions.

2.4.2 Rapid fixation in a drying cabinet

Working method: ■ Prepare dye and alkali solutions separately ■ Prepare the fabric sample ■ Pad at 3 m/min ■ The pick-up should correspond to that in practice (2 immersions

have proved advantageous) ■ Place the padded sample in a polyethylene bag and dwell for at

least 15 min at room temperature ■ Store the padded sample, in the polyethylene bag, for 1h at 50 °C

in drying cabinet (constant temperature must be maintained)

After fixation the samples are rinsed and soaped in the usual

manner.

It is advisable to compare the shade found using a drying cabinet

against that obtained by standard batching conditions.

2.4.3 Examples

Shade 12.2 g/l Drimaren® Yellow HF-CD

1.2 g/l Drimaren® Red HF-CD

1.2 g/l Drimaren® Aquamarine HF-CD

1.0 g/l Leonil® EHC liq c

50.0 ml/l Sodium silicate 38 °Bè

8.0 ml/l NaOH 36 °Bè

Shade 24.0 g/l Drimaren® Yellow HF-CD

6.5 g/l Drimaren® Red HF-CD

11.0 g/l Drimaren® Aquamarine HF-CD

1.0 g/l Leonil® EHC liq c

50.0 ml/l Sodium silicate 38 °Bè

15.0 ml/l NaOH 36 °Bè

2.5 Clariant tailing test

Tailing is responsible for shade differences between the beginning

and end of a batch in a continuous process.

Clariant has developed a very severe test which imitates this

phenomenon:

Prepare 500 ml dye liquor.liquor collected

from Step 2

Step 1 Step 2 Step 3

Reference

9 h, at 25 °C

Microwave

CMC 0.9, 105%

15 min RT

+ 4 min at

500 W

Drying cabinet

CMC 0.7, 97%

15 min RT

+ 60 min at

50 °C

Reference

15 h, at 25 °C

Microwave

CMC 0.6, 101%

15 min RT

+ 4 min at

500 W

Drying cabinet

CMC 0.7, 97%

15 min RT

+ 60 min at

50 °C

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Step 1 (beginning)

Pad 20 cm CO-merc. through 100 ml dye liquor from the 500 ml

prepared. A fixation step follows to fix the dyestuff.

Step 2

5 m CO merc. is passed through the remaining 400 ml dye liquor

then squeezed on the lab padder. The squeezed liquor is collected.

Step 3 (end)

Pad 20 cm CO-merc. through the collected liquor. A fixation step

follows to fix the dyestuff.

Assessment is carried out at the beginning (Step 1) and at the

end (Step 3) by comparison with each other. The differences in

concentration and shade are determined colorimetrically.

Reference or 100% is always the beginning. The less tailing there

is, the smaller the difference between the beginning and the end

(shade and strength). The test can be used to assess tailing in pad

batch and all continuous dyeing processes.

2.6 Shade change during drying

Depending on the dyestuff, but regardless of the substrate,

changes of shade can occur after the drying operation. This shade

change is dependent on the fabric temperature, pH and moisture

content.

A stable final shade is only achieved when the fabric pH is neutral

and the temperature and moisture content have reached

equilibrium.

It is therefore important that the shade is assessed against the

standard once this equilibrium has been reached. A conditioning

cabinet (e.g. 20 °C, 65% RH) can be used to condition samples

before assessing the shade.

3. Pad Dry Chemical Pad Steam process

3.1 Introduction

This is a continuous process for dyeing cellulosic fabrics with

Drimaren® HF/CL dyes. The process is particularly suitable for

dyeing large production batches, where the process becomes

economically attractive.

The pad dry chemical pad steam process offers the following advantages:

■ Simple working method ■ Short preparation time ■ High color yield ■ Excellent surface appearance even with heavy, tightly woven

fabrics ■ Excellent reproducibility ■ No risk of dye hydrolysis ■ Tailing with pale shades should not be an issue ■ Especially recommended for very large batches


The principle of the Pad Dry Chemical Pad Steam process consists

of padding the goods with dye solution at room temperature and

then drying. The dried goods are then padded with chemical pad

liquor and the dye fixed in a steamer.

The unfixed dye is removed by rinsing then soaping at the boil. This

washing off treatment is essential to obtain the optimum wet

fastness properties and final shade.

Dyepad liquor

Drying Chemicalpad liquor

Steaming

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■ The prepared state of the material to be dyed ■ Preparation of the dye pad liquor ■ The intermediate drying step ■ Preparation of the chemical pad liquor ■ Padding ■ Fixation by steaming ■ The washing off process


See section 2.3.1 “Fabric requirements”.


See section 2.3.1.1 “Sewing together the pieces”.

3.3.2 Preparation of the dye pad liquor

Standard recipe:

x g/l Drimaren® HF/CL dye

5–20 g/l Solidokoll® NX liq




See section 2.3.2.1 “Dissolving the dyes”

3.3.2.2 Pad liquor stability

The stability of the dye solution is very good because the dye pad

liquor doesn’t contain alkali.

3.3.3 Padding

See Section 2.3.5 “Padding”.

See Section 2.5 “Clariant tailing test”

3.3.4 Intermediate drying

The fabric is first passed through an infra-red pre-drier to reduce

the fabric moisture content to below ~35% in the absence of strong

air flow and fabric to metal contact, which accelerate dye

migration.

The drier used should ensure that the fabric is dried uniformly, over

its entire width and length (uniform air flow and temperature).

Residual humidity should not exceed 10–15% and should be

constant. The dried fabric should be allowed to cool before

steaming (uniform temperature and moisture content).

Intermediate drying has the following advantages: ■ The appearance of the goods is excellent ■ The dye stability is very good ■ Very deep shades are attainable

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Intermediate drying has the following disadvantages: ■ It makes the process slightly more expensive

3.3.4.1 Explanation of migration

During pre-drying the dye liquor may migrate, by means of capillary

forces, from the wetter (cooler) to drier (hotter) areas of the fabric

resulting in face to back or side to center shade variation. Dye

molecules continue to migrate as long as free water molecules

diffuse from the surface of the fabric. Migration stops when only

bonded water molecules remain and the moisture content of the

fabric has dropped below 30%. Infra-red pre-driers are used to

reduce the fabric moisture content to below ~35% in the absence

of strong air flow and fabric to metal contact, which accelerate dye

migration. Clariant has developed a very severe test which imitates

this phenomenon.

3.3.4.1.1 Clariant migration test

The fabric is padded with dye solution, at room temperature then

dried at 110 °C for 90 seconds. Before drying, a watch glass is

placed on the wet fabric. A damp atmosphere develops in the

watch glass and the dye solution migrates to the hotter areas. See

following illustration:

Inside

Outside

Fig: Example of dye migration after drying

Assessment is made colorimetrically by measuring the difference in

color strength between the inside and outside.

Reference of 100% is always outside. The less migration there is,

the smaller the difference between inside and outside.

High affinity dyes migrate slower than low affinity dyes as the

probability of dye adsorption on the fiber surface is higher. If the

dye affinity is too high then the tailing and washing off properties

become an issue. Migration can also be drastically reduced by

adding electrolyte, however this may result in tailing.

As a guide it can be said that if a value of > 60% is determined in

the Clariant migration test, the dye exhibits minimum migration and

is suitable for this process.

The dye selection guide provided has been optimized so that

migration and tailing are as minimal as possible.

3.3.5 Preparation of the chemical pad liquor

Standard recipe:

250 g/l Na2SO4 or NaCl

20 g/l Soda ash

10–20 ml/l Caustic soda 36 °Bè

10 g/l Revatol® NS liq c

The alkali required for fixation, electrolyte and Revatol® NS liq c are

pre-dissolved then added together, cold, to the feed tank. The liquor

volume is then adjusted as required with cold water. The electrolyte

in the chemical pad liquor reduces bleeding of the dye into the

chemical pad trough as it has only been dried and not fixed. The

electrolyte also improves dye diffusion inside the fiber during

steaming.

3.3.6 Padding


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3.3.7 Fixation by steaming

Padding temperature: 20–30 °C

Fixation: 60 seconds with saturated steam at 102–104 °C

In a fully continuous operation, the machine running speed is

governed by the time required to pre-dry the fabric. This is

determined by the fabric weight, the moisture content of the wet

fabric, the drying temperature, the airflow speed and machine

capacity. When processing heavy weight fabrics a slower running

speed may be necessary resulting in longer steaming times.

Extended fixation times do not affect the yield of Drimaren® HF dyes

due to the high alkaline stability of the dye-fiber bond. The dye-fiber

bond of certain elements from the Drimaren® CL range can be

sensitive to prolonged steaming times. Care should be taken to

adhere to the recommended fixation time.

3.3.8 Washing off


washed off material. Washing off is usually carried out on an open-

width washing machine. The soaping step is carried out with an

addition of Ladipur® RSK/R3C liq See Section 2.3.7 “Washing off”.


See Section 2.6 “Shade change during drying”

4. Pad Wet Steam process

4.1 Introduction

This is a steaming process without intermediate drying for the

continuous dyeing of cellulosic fabrics with Drimaren® HF/CL dyes.

This process is especially suitable for heavy fabrics such as

corduroy, velvet or toweling where it is impossible to control dye

migration if an intermediate drying step is used.

The pad wet steam process offers the following advantages:

■ Omission of an intermediate drying stage saves energy ■ No dye migration ■ Simple process ■ Short preparation time

The pad wet steam process has the following disadvantages:

■ Shade build-up is inferior to other continuous dyeing processes,

therefore it is only economical for dyeing large batches ■ This process is not recommended for tightly constructed or

mercerized fabrics


The principle of the pad wet steam process consists of padding the

SteamingDyepad liquor

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fabric with dye solution at room temperature, followed directly by

fixation in a steamer. Unfixed dye is removed from the fiber by rinsing

then soaping at the boil. This washing off treatment is essential to

obtain the optimum wet fastness properties and final shade.




■ The prepared state of the material to be dyed ■ Preparation of the pad liquor ■ Padding ■ Fixation by steaming ■ The washing off process


See Section 2.3.1 “Fabric requirements”.


See Section 2.3.1.1 “Sewing together the pieces”.



10–20 g/l Soda ash

20–40 g/l Glauber’s salt


10 g/l Revatol® NS liq c


Glauber’s salt is recommended for the highest solubility. The amount

of Glauber’s salt can be increased when dyeing very deep shades

to improve the yield, however, this could have a negative influence

on the solubility and tailing behavior of certain dyes.

An addition of 100 g/l urea is therefore recommended to prevent

dyestuff precipitation, with certain dyes, at high concentrations.

Depending on the article and dyestuff concentration, preliminary

lab trials are recommended.

For reasons of solubility an addition of 100 g/l urea is recommended

for Drimaren® Scarlet HF-3G, Drimaren® Yellow HF-CD, Drimaren®

Turquoise CL-B, Drimaren® Green HF-5BL and Drimaren® Turquoise

K-2B at all concentrations.


See Section 2.3.2.1 “Dissolving the dyes”.

4.3.2.2 The alkali liquor

The alkali necessary for fixation is pre-dissolved then added, cold,

to the feed tank. The liquor volume is then adjusted as required

with cold water.

4.3.2.2.1 Working without a metering pump

If a metering pump isn’t available then special attention must be

paid to the pad liquor stability. If the dyestuff is dissolved warm or

hot then care should be taken to add the soda ash to the cooled

pad liquor. Some dyes may precipitate if the pad liquor is allowed to

stand too long before use.

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The alkali required for fixation is pre-dissolved then added, cold, to

the feed tank. The alkali is added last, immediately before the

production run.


4.3.3.1 Pad liquor stability with a metering pump

The separately prepared dye and alkali solutions are cooled to pad

liquor temperature and sent to the padder via a mixing device. A

mixture ratio of 4 parts dye solution and auxiliaries to 1 part alkali

solution has provided good results in practice. Other mixture ratios

are also possible. If a metering pump is used the pad liquor stability

isn’t normally an issue.

4.3.3.2 Pad liquor stability without a metering pump

After mixing with alkali the dye becomes reactive. To ensure

optimum pad liquor stability, i.e. to avoid premature dye hydrolysis,

the temperature should be kept at 25 °C +/– 3 °C where possible.

All reactive dyes are subject to hydrolysis in the presence of alkali

in the pad liquor. It depends on the time, amount of dye and

temperature. Hydrolyzed dye cannot react with the cellulose. If dye

hydrolysis already takes place in the pad liquor or in the padding

trough there is a danger of tailing. Exact knowledge of the pad

liquor stability of the Drimaren® HF/CL dyes is therefore important.

Details of individual dyes can be found in the shade card inserts.

4.3.4 Padding


See Section 2.5 “Clariant tailing test”





Turquoise CL-B and Drimaren® Turquoise K-2B require 90–180

seconds steaming time, depending on the depth of shade, to

achieve full fixation.

The fabric is padded with the dye solution then passed directly into

the steamer.

In a fully continuous operation, the machine running speed is

governed by the time required to dry the fabric, usually on a

cylinder drier, after passing through a continuous washing range.

This can result in longer steaming times. Extended fixation times do

not affect the yield of Drimaren® HF dyes due to the high alkaline

stability of the dye-fiber bond. The dye-fiber bond of certain

elements from the Drimaren® CL range can be sensitive to

prolonged steaming times. Care should be taken to adhere to the

recommended fixation time.

4.3.6 Washing off

See Section 2.3.7 “Washing off”.


See Section 2.6 “Shade change during drying”

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5. Pad Thermofix process

5.1 Introduction

After padding and intermediate drying the dyestuff is fixed by hot

air in a hotflue. This process is used for the continuous dyeing of

cotton fabrics with Drimaren® HF/CL dyes.

Dyepad liquor

Drying Fixation

The pad thermofix process offers the following advantages:

■ Simple process ■ Short preparation time ■ Good lab to bulk shade reproducibility

The pad thermofix process has the following disadvantages:

■ Build-up ■ Reduced light and chlorine fastness ■ The process requires urea


The principle of the pad thermofix process consists of padding the

goods with dye solution at room temperature and then drying. The

dried goods are then fixed at 150–180 °C.

Unfixed dye is removed from the fiber by rinsing then soaping at the

boil. This washing off treatment is essential to obtain the optimum

wet fastness properties and final shade.




■ The prepared state of the material to be dyed ■ Preparation of the pad liquor ■ Padding ■ Intermediate drying ■ Fixation by hot air ■ The washing off process




See Section 2.3.1.1 “Sewing together the pieces”.



y g/l Alkali




50–150 g/l Urea

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Drimaren® HF/CL dye g/l 0–5 5–10 10–20 20–40 > 40

Urea g/l 50 75 100 150 150

Sodium bicarbonate g/l 15 15 15 – –

Soda ash g/l – – – 10 20

5.3.2.1 Influence of urea

The recommended amount of urea can be reduced for very pale

shades. Reducing the amount of urea may lead to a loss in color

strength depending on the dyes used and depth of shade. 5–10 g/l

Borax can be added to the pad liquor to prevent yellowing of the

cotton fiber at temperatures >160 °C.

5.3.3 Dissolving the dyes

See Section 2.3.2.1 “Dissolving the dyes”

5.3.4 The alkali liquor

The alkali necessary for fixation is pre-dissolved then added, cold,

to the feed tank. The alkali is added last, immediately before the

production run.

5.3.4.1 Working without a metering pump

See Section 4.3.2.2.1 “Working without a metering pump”.


See Section 4.3.3 “Pad liquor stability”.

5.3.5.1 Pad liquor stability with a metering pump

See Section 4.3.3.1 “Pad liquor stability with a metering pump”.

5.3.5.2 Pad liquor stability without a metering pump

See Section 4.3.3.2 “Pad liquor stability without a metering pump”.

5.3.6 Padding


See Section 2.5 “Clariant tailing test”.


See section 3.3.4 “Intermediate drying”.

See section 3.3.4.1 “Explanation of migration”.

See section 3.3.4.1.1 “Clariant migration test”.

5.3.8 Fixation in hot air


Fixation: 60 seconds with hot air at 160 °C

The fabric is padded with the dye solution, dried and then fixed at

150–180 °C.

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The fixation time and temperature may vary depending on the

machine configuration, dye and depth of shade. In general,

however, it is very short (60 s). Longer fixation times don’t have a

negative effect on the yield but may impair the light fastness.


Turquoise CL-B and Drimaren® Turquoise K-2B require 90–120

seconds thermofixation time, depending on the depth of shade, to

achieve full fixation.

5.3.9 Washing off



See Section 2.6 “Shade change during drying”.

6. Pad Moist process

6.1. Introduction

The Pad Moist process is a continuous dyeing procedure used for

dyeing cellulosic fabrics with Drimaren® HF/CL dyes. The principle

of the process consists of padding the fabric with dye solution at

room temperature before passing it through a hot flue with an air

temperature of 110–130 ºC and a relative humidity of 25–30 % inside

each chamber. Under these conditions the fabric is dried and at the

same time dyestuff fixation takes place at 68–71 ºC (the wet bulb

temperature).

The unfixed dye is removed by rinsing then soaping at the boil. This

washing off treatment is essential to obtain the optimum wet

fastness properties and final shade.

Dyepad liquor

Drying/Fixation

The Pad Moist process offers the following advantages: ■ Fully continuous dyeing process ■ Ideal for short or long production batches ■ Low chemical load in the waste water (no urea, salt or sodium

silicate) ■ High fixation yield ■ Simple working method ■ Short setting up and machine down time

The Pad Moist process has the following disadvantages: ■ Machine size must be adapted for heavy weight fabrics (longer

drying time) ■ Laboratory shade matching requires special equipment


The reactive dyes are fixed during 2–4 minutes (depending on

fabric weight and machine capacity). under controlled humidity

(25–30 % steam content) and an air temperature of 110–130 °C.

Infrared pre-drying increases productivity when dyeing heavy

weight fabrics. The dry goods are then washed off (preferably

continuously) to remove the unfixed dyestuff from the fibers.




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■ The prepared state of the material to be dyed ■ Preparation of the pad liquor ■ Padding ■ Drying/fixation ■ The washing off process



6.3.2 Sewing together the pieces

See Section 2.3.1.1. “Sewing together the pieces”.

6.3.3 Preparing the dyestuff pad liquor

Standard recipe:x g/l Drimaren® HF/CL dye

y g/l Alkali



6.3.4 Dissolving the dyestuffs

See Section 2.3.2.1. “Dissolving the dyestuffs”.

6.3.5 The alkali liquor

Here the alkali necessary for fixation is pre-dissolved the added,

cold, to the feed tank, before the volume is adjusted as required

with cold water. A metering device is required to guarantee

sufficient dye liquor stability.


Soda ash g/l 10 20 20 20 20

Caustic soda 36 °Bè g/l – 1.0 2.0 3.0 4.0


Soda ash g/l 20 20 20 20 20

Caustic soda 36 °Bè g/l 5.0 6.0 7.0 8.0 10.0

For Drimaren® Black CL-S at concentration greater than 60 g/l the

amount of caustic soda should be increased to 15–20 ml/l.


The dyestuff and alkali solutions, which have been prepared

separately, are cooled to room temperature then fed into the

padder via a mixing device. A mixture ratio of 4 parts dye solution

and auxiliaries to 1 part alkali solution has provided good results in

practice. Other mixture ratios are also possible. The program

«MOISTFIX» in the electronic shade card can be used to calculate

the exact alkali requirements as well as the pad liquor stability and

required drying/fixation time.

6.3.7 Padding



6.3.8 Drying/Fixation

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After applying the pad liquor solution on the padder, the dyestuff is

fixed and the material dried in an atmosphere of controlled humidity

(25–30 % steam content) and an air temperature of 110–130 °C.

Here the fixation time and the running speed must be adapted to

the quality of the material (usually between 2 and 4 minutes).

6.3.9 Washing off




7. SWIFT process for dyeing PES/CEL blends

7.1 Introduction

The SWIFT process is a one bath, 2 stage process for dyeing PES/

CEL fabrics with Foron® S-WF and Drimaren® HF dyes, where high

wash fastness is achieved without a reduction clearing step.

Disperse and reactive dye can be padded together and the whole

process is completed with one pass through a continuous dyeing

range.

The key to success is the dyestuffs selected:

Foron® S-WF dyes: A range of alkali clearable disperse dyes with

high sublimation fastness. High wash fastness can be achieved in

continuous dyeing without an intermediate reduction clearing

process. Foron® S-WF dyes show minimum sensitivity to

temperature fluctuations within their maximum fixation range (205–

225 °C depending on the fixation time). The danger of center to

selvedge and beginning to end shade differences can largely be

eliminated guaranteeing excellent reproducibility.

Drimaren® HF dyes: Reactive dyes with very high fixation values

and high diffusion that guarantee excellent washing off properties.

High wet fastness can be achieved by soaping at 85 ºC with only

one pass through a continuous washing range. High alkaline

stability of the dye-fiber bond (DFP chemistry) is essential as the

washing off procedure must be carried out under alkaline

conditions.

Dyepad liquor

Dry Thermosol Chemicalpad liquor

Steam

The SWIFT process offers the following advantages:

■ Simple working method ■ Suitable for dark shades ■ Increased productivity ■ Reduced water, energy and chemical consumption ■ Excellent surface appearance even with heavy, tightly woven

fabrics ■ Excellent reproducibility ■ High level of wet fastness is achieved without a costly reduction

clearing process ■ Especially recommended for very large batches


The principle of the SWIFT (Pad Dry Thermosol Chemical Pad

Steam) process consists of padding the goods with dye solution at

room temperature and then drying. A thermosol step follows to dye

the polyester part of the blend with Foron® S-WF dye. The dried

goods are then padded with a chemical pad liquor before steaming

to fix the Drimaren® HF dye on the cellulose part of the blend.

During the alkaline steaming process, unfixed Foron® S-WF dye,

adhering to the fabric surface, is converted to a water soluble

anionic form. It can then be removed together with the unfixed

reactive dyestuff by the subsequent washing off process.

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■ The prepared state of the material to be dyed ■ Preparation of the dye pad liquor ■ The intermediate drying step ■ The thermosol step ■ Preparation of the chemical pad liquor ■ Padding ■ Fixation by steaming ■ The washing off process


See section 2.3.1 “Fabric requirements“.


See section 2.3.1.1 “Sewing together the pieces”.

7.3.2 Preparation of the dye pad liquor

Standard recipe:

x g/l Drimaren® HF dye

y g/l Foron® S-WF dye




5–30 g/l Emigen® DPR liq


For preparation of the reactive dye see section 2.3.2.1 “Dissolving

the dyes”. The disperse dye is dispersed by pouring it into warm

water (40 °C) and stirring. The time required for mixing the dye

liquor must be adapted to the total dye concentration and the dyes

being used.

Before adding dissolved dyes to the feed tank the dye liquor should

be passed through a filter to ensure that any non-dissolved dye or

contamination is held back. Unlevelness and/or spots and possible

damage to the pumps can be avoided in this way.

Cold water should then be used to adjust the dye liquor to the

required volume.

7.3.2.2 Pad liquor stability

The stability of the dye solution is very good because the dye pad

liquor doesn’t contain alkali. The pad liquor mixer should remain

running to prevent settling out of the disperse dye.

7.3.3 Padding




See section 3.3.4 “Intermediate drying”.

See section 3.3.4.1 “Explanation of migration”.

See section 3.3.4.1.1 “Clariant migration test”.

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7.3.5 Thermosoling

After the intermediate drying process the disperse dye is

micro-dispersed on the surface of the polyester fiber, or in the case

of PES/CEL blends, to a large extent on the cellulosic fiber. In the

thermosol process, the fabric is treated in hot air at 210–220 °C for

45–60 seconds.

The thermosol process can be divided into 3 steps: ■ Heating of the fabric ■ Adsorption of the disperse dyestuff on the polyester fiber

surface ■ Dye diffusion and distribution inside the polyester fiber

7.3.6 Preparation of the chemical pad liquor

See section 3.3.5 “Preparation of the chemical pad liquor”.

7.3.7 Padding


The liquor pick-up on PES/CEL fabrics is usually ~35–45 % using a

conventional padder. This isn’t high enough to obtain the required

amount of chemical liquor on the fabric. Pad-steam machinery

therefore incorporates either a booster, kiss roll or flex nip system

to ensure that the liquor pick-up is high enough (> 100 %) for

fixation of the reactive dye and clearing of the disperse dye (that

remains on the fiber surface) during the steaming process.




In a fully continuous process, the machine running speed is

governed by the time required to pre-dry the fabric. This is

determined by the fabric weight, the moisture content of the wet

fabric, the drying temperature, the air flow speed and machine

capacity. When processing heavy weight fabrics a slower running

speed may be necessary resulting in longer steaming times.

Extended fixation times do not affect the yield of Drimaren® HF dyes

due to the high alkaline stability of the dye-fiber bond. During the

alkaline steaming process, unfixed Foron® S-WF dye, adhering to

the fabric surface, is converted to a water soluble anionic form. It

can then be removed together with the unfixed reactive dyestuff by

the subsequent washing off process.

7.3.9 Washing off


washed off material. Washing off is carried out on a continuous

open-width washing machine.

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The fabric is washed off under alkaline conditions to ensure that all

unfixed disperse dye remaining on the fiber surface is converted to

the water soluble anionic form that can be removed together with

the unfixed reactive dye. For this reason it is necessary to use

Drimaren® HF dyes due to the high alkaline stability of the dye-fiber

bond.

The unfixed dye is removed by rinsing then soaping at 85 °C. Higher

temperatures are avoided to prevent migration of disperse dye,

from within the polyester fiber structure to its surface, thus averting

wet fastness issues. Disperse dyes begin to migrate at

temperatures above the glass transition temperature (Tg) of the

polyester fiber. Drimaren® HF dyes, having excellent washing off

properties, can be washed off at 85 °C. This washing off treatment

is essential to obtain the optimum wet fastness properties and final

shade.

Continous washing range with 8 compartments:


2. Wash at 85 °C

3. Wash at 85 °C with 1–3 g/l Eganal® DFT liq

4. Wash at 85 °C


6. Wash at 85 °C

7. Wash at 85 °C

8. Neutralize at 40–60 °C to pH 6–7 with Sirrix® NE liq



8. Dye Selection

State of the art, problem solving range, for difficult pale to medium

shades requiring high light fastness ■ Drimaren® Golden Yellow HF-CD (non photochromic element) ■ Drimaren® Yellow HF-CD (non photochromic element) ■ Drimaren® Red HF-CD ■ Drimaren® Aquamarine HF-CD

Top performing elements to meet the highest fastness and

reproducibility demands in medium to dark shades ■ Drimaren® Golden Yellow HF-CD ■ Drimaren® Dark Red HF-CD ■ Drimaren® Red HF-3B ■ Drimaren® Aquamarine HF-CD ■ Drimaren® Dark Blue HF-CD ■ Drimaren® Navy HF-GN ■ Drimaren® Navy HF-B

Cost-effective range recommended for dyeing standard articles in

medium to dark shades ■ Drimaren® Yellow CL-2R ■ Drimaren® Red CL-5B ■ Drimaren® Red CL-4B ■ Drimaren® Dark Red HF-CD ■ Drimaren® Navy CL-R ■ Drimaren® Black CL-S

Special elements for bright yellow, blue, green and turquoise

shades ■ Drimaren® Brilliant Yellow HF-RL ■ Drimaren® Turquoise CL-B ■ Drimaren® Turquoise K-2B ■ Drimaren® Royal Blue HF-CD ■ Drimaren® Green HF-5BL

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Clariant International LtdRothausstrasse 614132 Muttenz

Switzerland

Business Unit Textile ChemicalsThe Synergy1 International Business Park609917 SingaporeSingapore

This information corresponds to the present state of our knowledge and is intended as a general description of our products and their possible applications. Clariant makes no warranties, express or implied, as to the information’s accuracy, adequacy, sufficiency or freedom from defect and assumes no liability in connection with any use of this information. Any user of this product is responsible for determining the suitability of Clariant’s products for its particular application.* Nothing included in this information waives any of Clariant’s General Terms and Conditions of Sale, which control unless it agrees otherwise in writing. Any existing intellectual/industrial property rights must be observed. Due to possible changes in our products and applicable national and international regulations and laws, the status of our products could change. Material Safety Data Sheets providing safety precautions, that should be observed when handling or storing Clariant products, are available upon request and are provided in compliance with applicable law. You should obtain and review the applicable Material Safety Data Sheet information before handling any of these products. For additional information, please contact Clariant.

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© 2011 Clariant International Ltd Rothaus-strasse 61, 4132 Muttenz, Switzerland

Documents

Reactive Continuous Dyeing