Econtrol Dyeing Process: An Ecological

and Economical Approach

Shamshad Ali, Zeeshan Khatri, and Khan Muhammad Brohi

Abstract Ecology and economy are among the most used catch words of our time,

and their significance is of the greatest possible importance for the survival of textile

industry. Econtrol dyeing process was introduced by Dystar and Monforts in ITMA

in 1995 to provide the textile dyer with a dyeing system that would produce a simple,

rapid, and economical, continuous dyeing method for cellulosic fibers with minimal

chemical usage. Themost significant and unique feature of this process is that it does

not use a separate fixation step, i.e., steaming, curing, or dwell time, which is essen-

tial and associated with the conventional reactive dyeing methods in practice. It can

be used to dye all ranges of shades that can be obtained with reactive dyes through

various dyeing processes on all cellulosic fibers such as cotton, viscose, tencel, and

linen. This paper represents a review of the economical and ecological merits

offered by this process in comparison with other continuous dyeing methods. The

example of Afroze Textile Mills Limited, Karachi, Pakistan, is provided as a case

study which is running this process successfully since last 5 years.

Keywords Continuous dyeing • Conventional reactive dyeing • Economical con-

tinuous dyeing • Econtrol dyeing

1 Introduction

To understand the emergence of the Econtrol process and its success, the following

points are to be considered by the dye houses.

1. The number of shades to be dyed has risen steadily with higher fastness

specifications.

2. Environmental regulations have become more stringent.

S. Ali (*)

Department of Textile Engineering, Mehran UET, Jamshoro, Pakistan

e-mail: shamshadonline@gmail.com

M.A. Uqaili and K. Harijan (eds.), Energy, Environment and Sustainable Development,DOI 10.1007/978-3-7091-0109-4_28, # Springer-Verlag/Wien 2012

291

3. Batch sizes have declined dramatically.

4. Delivery times are reduced [1].

Traditionally, four dyeing processes have been employed to dye cotton and

viscose with reactive dyes by continuous method (Fig. 1). They are as follows:

1. Cold pad-batch.

2. Pad-dry Thermofix.

3. Pad steam.

4. Pad-dry chemical pad-steam [2].

The characteristic features of the mentioned continuous reactive dyeing pro-

cesses for cellulosic fibers are given in Table 1.

The selection of dyeing process depends upon many factors, most importantly the

cost of the process. Most of the processes use high temperature (100–160�C) andhazardous chemicals (urea, sodium silicate, and salt) in order to achieve maximum

yield.

The limitations of these dyeing processes are listed in Table 2.

Table 1 Characteristic features of continuous reactive dyeing processes [3]

Processes Drying Fixation (�C) Fixation medium

Pad-batch – 20–35 Padding liquor

Pad-wet steam – 102 Steam 100%

Pad Thermofix 110–130�C 160 Air

Pad-dry chemical pad-steam 110–130�C 102 Steam 100%

Fig. 1 Most common dyeing methods for cellulosic fibers

Table 2 Limitations of most common dyeing processes [3]

Dyeing process Drawbacks

Pad-batch High fixation time, bath stability

Pad-dry Thermofix Low light fastness, damage of elastan, yellowing

Pad-wet steam Limited yield, tailing

Pad-dry chemical pad-steam Special machine necessary, high energy demand

292 S. Ali et al.

2 Econtrol Dyeing Process

The Econtrol process was developed jointly by Dystar and Monforts. It is one of the

few real inventions in process development and machinery in recent years.

It comprises just three steps: Application of the dyes through padding, drying in

moist condition, and washing off [4], as shown in Fig. 2.

The dyeing range is a simple arrangement shown in Fig. 3. The range is started

with a lead fabric, which brings water into the installation through the wetting

arrangement in order to establish the chamber climate. The jet temperature is

120�C. After a short time, the bath containing the dye liquor is raised and the fabric

is impregnated with dyestuff. When the dye goods reach the wetting arrangement,

this is turned away. A measuring device controls and regulates the steam content

of the atmosphere in the hotflue. The goods dwell for 2 min in the hotflue and

the reactive dyestuff is fixed to the fiber with a high yield [2, 5]. Owing to the mild

fixation climate in the machine compared to that in other common dyeing pro-

cesses, soft fabric handle is obtained. Econtrol is the registered trade mark

of Dystar.

Fig. 3 Econtrol process steps. (1) Feeding section, (2) pad mangle, (3) wetting unit, (4) Thermex

hotflue, (5) measuring and control unit (chamber atmosphere), (6) steam injection unit, (7) outlet

section

Fig. 2 Econtrol continuous

dyeing method for cellulosic

fibers

Econtrol Dyeing Process: An Ecological and Economical Approach 293

2.1 Role of Humidity

It is worth mentioning here that fixation of reactive dyes is impossible in normal

drying conditions. During drying, the temperature of the moist good is far lower

than the surrounding temperature. The fabric temperature depends on the humidity

of the air used to dry it [1].

If humidity is 25% and the air temperature is 120�C, the temperature on the

surface of the goods is around 68�C. If humidity is increased to 30%, the tempera-

ture on the goods is around 71�C (see Fig. 4). The Econtrol process uses this

physical fact to fix the reactive dye during drying. Three key variables, time,

temperature, and humidity, are used to ensure accurate control of the dyeing process

in the Thermex Hotflue. The goods should spend about 2–3 min in the chambers

[1, 2]. The presence of humidity in the fixation chamber assists in the diffusion of

dyes inside the fabrics with compact weave structure.

2.2 The Process Edge

The process is developed to achieve optimum results in the shortest possible time.

The fewer the variables affecting the dyeing process, the higher the probability of

achieving this goal. Tolksdorf reported 25 variables in pad-dry chemical pad-steam

process that can adversely affect the dyeing process. By contrast, Econtrol process

has 15 dyeing process variables (40% reduced). This is owing to the fact that the

00 0

20

20

30

10

40

40

50

60

60

80

100Moisture content of the fabric Fabric temperature

final fixation

Fixation conditions:Surrounding temperature: 120 - 130°C, humidity: 25 - 30%

Wetbulb temperature68 - 69 °C

120 °C120

0,5 1,51,0 2,0time [min]

Hum

idity

in th

e fa

bric

[%]

Fab

ric te

mpe

ratu

re [°

C]

Fig. 4 Econtrol – material temperature and humidity of the goods [6]

294 S. Ali et al.

Econtrol process does not use a separate fixation step, which is, curing, steaming, or

batching [1].

Likewise, improved light fastness rating is obtained because there is no urea

present in the recipe, and the absence of salt is helpful in the washing-off process

[2]. Similarly, 35% less time will be needed for Econtrol process in lab matching

when compared against the pad-dry chemical pad-steam process [1].

Figure 5 shows the amount of various chemicals used by different dyeing

processes in the dyeing of ten million meters of fabric.

It is interesting to note here that the most environment-friendly process is often

also the most economical. Econtrol is a relevant example to quote. By eliminating

the need of curing/steaming stage, huge amount of energy can be saved [1].

Similarly, there is no need to go for harsh chemicals such as salt, urea, and

sodium silicate. It would eventually extend the life of the dyeing machine. More-

over, since they do not have to wash out, they cannot contaminate effluent or

exhaust air. Econtrol process is, therefore, both economical and eco-friendly. This

process can be used for fabrics weighing 70–500 g/m2.

Depending upon the working conditions in production plants, Table 3 presents

the summary of average depth of shade obtained from dyeing processes.

0

100

200

300

400

500

600

PDCPS PDC CPB ECONTROL

Reactive Dyeing Processes

Che

mic

al c

onsu

mpt

ions

in

Ton

s

Fig. 5 Chemical

consumptions in continuous

dyeing

Table 3 Depth of shade

(yield) of different dyeing

processes [3]

Dyeing process Yield (%)

Pad moista 100 (as a standard)

Pad-batch 95

Pad-dry Thermofix 95

Pad-wet steam 85

Pad-dry chemical pad-steam 105aThe Econtrol process offered by Clariant

Econtrol Dyeing Process: An Ecological and Economical Approach 295

3 Industrial Production: A Case Study

In Pakistan, Afroze Textile Mills Limited situated in Karachi is the leading dye

house that is running the Econtrol process successfully since the last 5 years. The

data taken from their production unit are listed in Tables 4 and 5.

Medium or highly substantive reactive dyes are selected for the dyeing process.

The dyeing recipe employed there with success is in the range of 40–100 g/L.

The Drimarene CL (Clariant) and Remazol RGB (Dystar) dyestuffs are used there.

There are three chambers in the Thermex Hotflue (Monforts) at Afroze Textile

Mills Limited; each chamber has a cloth content of 32 m length.

The bulk production is achieving 25% greater depth of shade from Econtrol

process than pad-dry cure process by using the same amount of dyestuff. In com-

parison with cold pad-batch process, they are getting similar fastness ratings except

light fastness, 1–2 rating less. The Econtrol process has replaced the pad-dry cure

process and the pad-dry chemical pad-steam process done for 100% cotton fabric

with reactive dyes in Afroze Textile Mills Ltd., Karachi, Pakistan.

4 Ecological Benefits

The Econtrol process simultaneously offers the following ecological benefit:

The combined reduction in the quantities of chemicals (urea, salt, and sodium

silicate), and dyes from the recipe, also the water used for washing-off process,

greatly cuts down the effluent load discharged from the dye house to the environ-

ment [2].

Table 4 Padding recipe used

for Econtrol process in Afroze

Textile Mills Limited

Reactive dyes Quantity (g/L)

Soda ash 20

Caustic soda 48�Be 10

Mild oxidizing agent 6

Antimigrating agent 10

Table 5 Process conditions

used for Econtrol process in

Afroze Textile Mills Limited

Parameters Range

Padding temperature 25�CDrying/fixation temperature 140�CDrying/fixation time 2 min

Humidity 25–30% volume

Steam regulation 50%

Exhaust air damper 30%

Speed of machine 50 m/min

296 S. Ali et al.

5 Economical Benefits

The Econtrol process offers the following significant economic advantages:

Lower chemical cost, this is owing to the elimination of the usage of various

chemicals and auxiliaries that include urea, salt, and sodium silicate, and are

considered essential for the reactive dyeing process.

Lower dyes cost, this is due to the higher fixation yield, that is, less dye would berequired to obtain the required depth of shade on the fabric.

Lower water cost, as a result of greater fiber–polymer reaction, the hydrolysis of

dyes will be lower and hence, the washing-off process would definitely utilize less

volume of water.

Lower energy cost, in consequence of the exclusion of the thermofixation step

during the continuous dyeing process on the Thermex Hotflue, reduced thermal

energy would be needed for the fiber–polymer reaction to take place.

The process also has a logistical benefit: As the fabric is in dry state at the end of

the Econtrol process, they do not have to be washed off immediately and can be

stored. Now it can be said that the new dyeing technology is more economical

despite its somewhat higher investment cost (hotflue plus accessories) [2].

6 Conclusions

The key issue that will concern the continuous dyer in the future would be the

search for the dyeing process which must be simple to use for ranges of shade, and

can provide the dyer the economy, even when dyeing small batches, and rapid color

change, as the duration of the fashion trend is on fall worldwide, plus it should be

reliable, due to excellent reproducibility, and without any harm to the environment.

The continuous dyeing on Thermosol machine would continue to deliver all these

features in the shape of economical and ecological dyeing process, that is, Econtrol.

Acknowledgments The authors are thankful to Mr. Kamran Khatri, Clariant Pakistan Limited,

Mr. Abdul Razak Khatri, Dystar Pakistan, for providing relevant data, and Mr. Shoaib Ansari,

Afroze Textile Mills Limited, Karachi, for his continuous help and support in this work.

References

1. Tolksdorf FP (2006) Econtrol - The modern art of continuous dyeing. Melliand Textilber

12:228–232

2. Wersch KV (1998) Economic and ecological aspects of the continuous dyeing of cellulosic

fibres. Melliand Textilber 79:166–167

3. Roth A (2007) Dyes for cellulosics – pad moist, Clariant Pakistan Limited, Karachi

4. http://www.ptj.com.pk/Web%202004/04-2004/dyster.html. Accessed Nov 2009

5. http://www.monforts.de. Accessed March 2009

6. General continuous processes by dye class, Dystar Pakistan Limited, Karachi, 2001

Econtrol Dyeing Process: An Ecological and Economical Approach 297