PROJECT - REACTION MECHANISM OF REACTIVE DYES IN ON CELLULOSE FIBER.

• Introduction • Raw Materials • Importance of The Survey • Reason of using Reactive dyes in major textile industry in Bangladesh • Methods of Dyeing & Printing Cotton Goods with React

Prepared By : Mazadul Hasan sheshir ID: 2010000400008

13th Batch (session 2009-2013) Department : Wet Processing Technology Email: mazadulhasan@yahoo.com

Blog : www Textilelab.blogspot.com (visit)

Southeast University

Department Of Textile Engineering

Prepared By :

• Introduction

• Raw Materials

• Importance of The Survey

• Reason of using Reactive dyes in major textile

industry in Bangladesh

• Methods of Dyeing & Printing Cotton Goods

with Reactive Dyes

• Technical Deficiency of Reactive Dyes, Causes

and Remedies of Technical Deficiency

• Conclusion

Chapter 1 Acknowledgement

Project Work is an academic function of the Pabna Textile Engineering College Our teacher Md Abdul Mannan,

Principal, Pabna Textile Engineering College, gave us an opportunity to choose preferable mills for Project Work I

chose Bengal Hurricane Dyeing & printing (pvt.) Ltd joyfully with the supervision of Mithun Biswas, Asst

Manager(production).

During the Project with Bengal Hurricane Dyeing & printing (pvt.) Ltd I worked in all the departments related with

Dyes and Chemicals Beside these, I learned about Dye Quality Control and Storage System,printing, Garments, Store & Inventory , finishing & specially dyeing.

Our deepest appreciation goes to Mithun Biswas, Asst Manager(production)Dyeing, Bengal Hurricane Dyeing &

printing (pvt.) Ltd to give us the opportunity to have project work at BENGAL HURRICAN GROUP.

I would like to thank Engr Md Iqbal Mahamud (Head of the Factory), GM, Dyeing, Bengal Hurricane Dyeing & printing

(pvt.) Ltd for helping to know about the all aspects of BENGAL HURRICAN GROUP.

I would also like to thank Tareq Ahmed(Deputy Manager),Md.Anwarul

Islam(Deputy Manager), Md Arif Rabbani Talukdar(Deputy Manager),Dyeing, Bengal Hurricane Dyeing & printing (pvt.) Ltd for helping to know about the all aspects of BENGAL HURRICAN GROUP.

Our gratitude also goes to all the employees of BENGAL HURRICAN GROUP for their sincere co-operation, support and

valuable advice which they have provided us during the two months of training.

Lastly I express my gratitude to our supervising teacher, the name that should be mentioned first, Shib Shankar

Chakraborty, Head of the Dept Wet Processing Technology for his valuable direction & supervision

However, I have prepared my Industrial Attachment overcoming all the difficulties & also the shortage of time Here I would like to present the report

•

Chapter:2 Application of reactive dyes in major

textile industries in Bangladesh

Application of Reactive dyes in major

textile industries in Bangladesh

Chapter:3 Project Abstract

•

The use of reactive for Dyed products has dramatically increased over the last 50 years Reactive dyes are now used to produce multiple products Reactive coloring components are inert into materials which are adhered to the base substrate by the application of soda ash which act as fixing agent

The main goal of our project is to provide information about the reason of using reactive dyestuff in major textile industry in Bangladesh, different methods using in our industry for cotton dyeing with reactive dyes, technical deficiency of reactive dyes during dyeing & causes and remedies of

deficiency of reactive dyes

During reactive dyeing there is a rule of using different amount of soda ash with fixed amount of salt & auxiliaries In case of dyeing of cotton with reactive dyes alkali pH should be correctly maintained

as during dyeing more electrolytes required for exhaustion and alkali for fixation

However the rubbing fastness and hand feel properties of dyed fabric depends on the amount of soda ash When we use fewer amounts of soda ash then hand feel is good but rubbing fastness is not good And when we use more amounts of soda ash then rubbing fastness is good but hand feel is not good

Chapter 4 INTRODUCTION

• With the evaluation of the wet processing industries the use of the reactive dyes in the most of the industries increases day by day As a result to complete the project it is has become a part to discus about the evaluation or growth of the wet processing industries in Bangladesh Now the number of

the wet processing industries and finishing industries in Bangladesh is 193 which are totally export

oriented according to the survey of the BTMA which has been provided into their we address.

• But the interesting matter is that with the growth of the textile wet processing mills the number of the employee is not increasing This is because of to reduce the cost and increase the quality the modernization of the machine is also increasing which reduce the number of worker in wet

processing industries But what is the actual number of the worker in wet processing industries has not been found due to the lack of proper survey in this sector

• Our project work was estimated as:

• APPLICATION OF REACTIVE DYES IN MAJOR TEXTILE IN BANGLADESH & DEFICIENCY OF REACTIVE

DYE:

• The project work is interesting as well as lengthy but we must admit that we had to really work hard and it helps us a great deal to know about whole procedure of reactive dyeing on dyed fabric Though reactive dyeing products exhibit intrinsic characteristics which make them suitable for multiple products application but reactive dye has it main problem with hydrolysis while dyeing as

a result wastage of the reactive dye increase and it become difficult to match the proper

The objects of project are:

 Knowing the source of textile raw materials of wet

processing and cost.

 To mention the reasons of using reactive dyes in major textile industry.

 To study on the application of reactive dyes

 To learn about the technical deficiency of reactive dyeing.

 To study the causes and remedy of deficiency of reactive dyeing

Chapter 5

RAW MATERIALS

• Raw material is a unique

substance in any production

oriented textile industry It

not only plays a vital role in

case of continuous

production & for high

quality fabric but also it is

related to the profit of the

industry.

Types of raw material

• The basic raw materials used in wet processing industries are:

• Fabric

• Dyestuffs

• Chemicals & auxiliaries.

•

Names & source

Fibres dyed:

By reactive dyes the

following fibres can be

dyed successfully:

1) Cotton, rayon, flax and

other cellulosic fibres.

2) Polyamide and wool

fibres.

3)Silk and acetate fibres

It covers a wide range of color spectrum and

includes shades varying from bright to heavy

Trade names

Some trade names of this dye are mentioned:

Trade name Manufacturer Country

Popularity of reactive dye:

Reactive are mostly used for dyeing cellulosic fibres At past cellulosic fibres were dyed with direct and vat dyes, but after the introduction of reactive dyes there utility has become limited Reactive dyes are superior to direct dye in the following aspects:

i) Ability to procedure bright shades of wide range.

ii) High leveling quality.

iii) Good washing fastness.

iv) Good light fastness.

And it is superior to vat dyes in the following aspects:

i) Simple dyeing method therefore one stage dyeing.

ii) Low temperature dyeing (below 1000C)

iii) Lower cost, i.e cheaper.

Again its dyeing process is fast and gives brighter shades than metallized azo dyes For the above reasons reactive dyes are more popular

NH (bridging part) C

C C

N Cl

N

N -N

N NH Hetreocyclic ring

The general structure of reactive dye is: D-B-G-X.

Chemical structure of reactive dyes

Here,

D= dye part or chromogen (color producing part) Dyes may be direct, acid, disperse, premetallised dye etc.

B = bridging part.

Bridging part may be –NH- group or –NR- group.

G = reactive group bearing part.

X= reactive group.

Classification of reactive dyes:

Reactive dyes may be classified in various ways as below:

1) On the basis of reactive group:

a) Halogen (commonly chlorine) derivatives of nitrogen containing heterocycle, like 3 types-

 Triazine group

 Pyridimine group

 Quinoxaline dyes

Example:

Triazine derivatives: procion, cibacron.

Pyridimine derivatives: reactone

Quinoxaline derivatives: levafix.

b)Activated vinyl compound:

 Vinyl sulphone

 Vinyl acrylamide

 Vinyl sulphonamide.

Example:

Vinyl sulphone: remazol

Vinyl acrylamide: primazine

Vinyl sulphonamide: levafix.

Classification of reactive dyes:

2) On the basis of reactivity:

a) Lower reactive dye:

Here ph is maintained 12-12.5 by using NaOH in bath.

b) Medium reactive dye: here pH is maintained 11-12 by using Na2CO3 in dye bath.

For example, Remazol, Livafix are medium brand dyes

c) Hot brand:

This type of dye contains reactive groups of least reactivity So high temperature

is required for dyeing i.e 720-930 C temperature is required for dyeing.

For example PRICION H, CIBACRON are hot brand dyes.

The reactive rate of some compounds are mentioned

Dyeing mechanism of reactive dye:

The dyeing mechanism of material with reactive dye takes place in 3

stages:-1.Exhaustion of dye in presence of electrolyte or dye absorption.

2.Fixation under the influence of alkali.

3.wash-off the unfixed dye from material surface.

•Now they are mentioned below:

1.Dye absorption:

When fibre is immersed in dye liquor, an electrolyte is added to assist the exhaustion

of dye Here NaCl is used as the electrolyte This electrolyte neutralize the negative charge formed in the fibre surface and puts extra energy to increase dye absorption So when the textile material is introduces to dye liquor the dye is exhausted on to the

fibre.

Dyeing mechanism of reactive dye:

2 Fixation:

Fixation of dye means the reaction of reactive group of dye with terminal –OH or-NH2 group of fibre and thus forming strong covalent bond with the fibre and thus forming strong covalent bond with the fibre This is an important phase, which is controlled by maintaining proper pH by adding alkali The alkali used for this

purpose depends on brand of dye and dyeing

temperature Here generally caustic soda, soda ash or NaHCO3 is used as alkali depending upon reactivity of dye They create proper pH in dye bath and do as the dye-fixing agent The reaction takes place in this stage

is shown below:

alkali

Application method of reactive dyes varies significantly with type of dyes, shade required, and available equipments in the mill These are 3 application procedures

available:

1 Discontinuous

method Conventional method

-Exhaust or constant temperature method

-High temperature method

-Hot critical method.

2 Cotinuous

-Pad-steam method -Pad dry method

- Pad thermofix method

3 Semi continuous

method Pad roll method

- Pad jig method

- Pad batch method.

Stripping of reactive dye:

1.Partial stripping:

Partial stripping is obtained by treating the dyed fabric with dilute acetic acid or formic acid Here temperature is raised to 70-100°C and treatment

is continued until shade is removed by desired amount After that a

through washing is necessary to remove the product of hydrolysis The amount of acid used is as below: -

Glacial acetic acid : 5-10 parts

With water :1000 parts

Or

Formic acid :2.5 to 10 parts

With water :1000 parts

Temperature : 70 - 100°C

Time : until desired shade is obtained.

2 Full stripping:

For complete stripping the goods are first treated with sodium

hydrosulphite (hydrose) at boil then washed off and bleached with 1%

sodium hypochlorite (NaOCl) at room temperature This is carried out for

30 min The recipe is as below:

Na-hypochlorite : 1% at room temperature

Na-hydrosulpite: at boil.

Time : 30 min D-R-Cl + H-OH D-R-OH

+ H-Cl

•Hydrolysis of activated vinyl compound containing dye,

D-F-CH2-CH2-OSO3H + H-OH D-F- CH2-CH2-OH + H2SO4

For preventing hydrolysis the following precautions are taken—

1.As hydrolysis increases with increasing temperature during dissolving and

application temperature should not be more than 40°C.

1.Dye and alkali solution are prepared separately and mixed just before using.

2.Dye and alkali should not be kept for long time after mixing.

Important factors for dyeing cellulosic fibre with cold brand reactive dye in batching process:

The important factors are as follows:

1) pH of the dye bath:

The optimum pH for fixing cold brand reactive dyes on cotton and viscose rayon depends on individual dyes, the temperature and time of dyeing pH decreases with increasing

temperature and time of dyeing For most of the dyes the optimum pH is 10.8 to 11 at 20o to

25oC Soda ash has been the best alkali for dyeing at 30oC for cotton, mercerized cotton and linen Increased fixation (due to higher temperature) and increased dye bath stability and better reproducibility are the advantages of soda ash as the fixing agent.

For viscose rayon the optimum pH is 10.3 at 20o to 25oC.

of the dye in the fibre increases with increased temperature At temperatures lower than

20oc, the rate of fixation is very low Hence for most of the dyes a temperature of 20o to 25oC

is the recommended temperature while for some other dyeing at 50o to 60oC with sodium bicarbonate as the alkali gives maximum color value.

Important factors for dyeing cellulosic fibre with

cold brand reactive dye in batching process:

5) Time of dyeing:

Generally the dye may be added in two portions The salt may also be added in two lots The exhaustion takes place in 20 to 30 min There is generally no advantage in extending the period beyond 30 min The alkali is then added and the dyeing

continued for 30 to 90 min The depth of shade and reactivity of the dye decide the time of dyeing For deeper shades larger times are required.

6) Liquor ratio:

With decreased liquor ratio, both exhaustion and fixation take place to increased exert However the rate of fixation of most of the dyes is not significantly affected

As the liquor ratio is decreased, the effectiveness of increasing salt addition also

decreases Hence lower amount of salt are sufficient to get optimum exhaustion.

•

Why low affinity reactive dyes are preferred for dyeing?

• If the reactivity of the dye is increased considerably, the rate of reaction with the fibre

increases There fore, the dyeing can be carried out in a short time However in this case the rate of dye also increases, leading to deactivation of a part of the dye This results in

wastage of the dye If on the other hand the reactivity of the dye is decreased, the extent of hydrolysis can be reduced considerably However this results in the slower rate of reaction with the fibre also The ultimate object of dyeing is to react as much of the dye ass possible with the fibre and minimize the hydrolysis of the dye This is achieved in practice in two

stages The dyeing is first started from the aqueous medium under neutral conditions when the dye does not react either with the fibre or with water Then gluber salt or common salt is added to exhaust the dye onto the fibre as much as possible In this respect, this stage of

dyeing (exhaustion) resembles the dyeing of direct dyes on cotton Then the second step (that

of fixation or reaction with the fibre) is carried out by adding the alkali (usually used soda ash) Since the exhausted dye is already on the fibre, it is more likely that the exhausted dye reacts with the fibre in preference to water However the dye present in the dye bath (which contains a substantial amount of the reactive dye) can now react with water since it is under alkaline condition It is already stated that the hydrolyzed dye cannot further react with the fibre but dye to the affinity forces; it is absorbed by the fibre and is retained in it During the subsequent washing or soaping the substantivity held hydrolyzed dye gets stripped into the treatment of the dyeing with boiling soap or detergent solution removes almost all hydrolyzed dye However if the affinity is very low, exhaustion of the dye bath prior to fixation cannot

be achieved substantially This results in a larger amount of the reactive dye remaining in the dye bath and getting hydrolyzed when alkali is added subsequently If the dye has high

affinity for cellulose like a direct dye, it becomes difficult to remove the hydrolyzed dye from the dyeing since it is also absorbed by and retained in the fibre by fairly strong affinity forces, through not as strong ass the covalent bond formed between the dye and the fibre Hence in actual practice low affinity dyes are selected for converting in to reactive dyes.

Dye Brand name Origin/source

REACTIVE

DYE

Dyestuffs:

Brand name Type Source

Novolube Jet Anti creasing agent Techna,Italy

Bluton BVB1 Violet tone brightener CHT,Germany Cibacel DBC Sequestering agent Ciba,India.

Cibafluid C Anticreasing agent Ciba ,Switz.

SandocleanPCLF Detergent Clarient,Germany

Cotton white T Redder tone brightener CHT,Germany

Cyclanon ECO Reduction cleaning agent BASF,Germany Jinlev RLF349 Dispersing agent Geigy,Taiwan Eulysin S pH buffer in PET dyeing BASF,Germany

Uvitex EBF Whitening agent Ciba ,Switz.

Jinlev CL-225 Levelling agent for reactive dye Geigy,Taiwan

-Palegal FA-8 Levelling agent for disperse dye BASF,Germany Respumit BU Antifoaming agent BASF,Germany Permacol SQ Sequestering agent Techna,Italy

Na thiosulphate Peroxide killer

-Uniperol O Washing agent for PET dyeing BASF,Germany Uvitex EVF PET brightener Ciba, Switz.

Uvitex 2B Yellow tone brightener Ciba ,Switz.

Mollan129 Soapinging agent Rota,dystar

-Reduction HCS Reduction cleaning agent Geigy,Taiwan Mollan130 Sequestering agent Rota,dystar

Bluton 2B Whitening agent Ciba,India

Chemicals:

• The annual requirement was not available & is a record

of the procurement department.