SOLVENT DYEING OF COTTON WITH ANIONIC DYES

by

J. VENKATA RAO

A thesis Submitted to the Indian Institute of Technology, Delhi

for the award of the Degree of

DOCTOR OF PHILOSOPHY

DEPARTMENT OF TEXTILE TECHNOLOGY INDIAN INSTITUTE OF TECHNOLOGY, DELHI

APRIL, 1982

01

CEERTIFIC TE

This is to certify that the thesis entitled

"SOLVENT DYEING OF COTTON WITH ANIONIC DYES",

submitted by Mr. J. Venkata Rao to the Indian

Institute of Technology Delhi, for the award of

degree of DOCTOR OF PHI10SOPHY is a record of the

bonafied research work carried out by him.

Mr. J. Venkata Rao has worked under my guidance for

the submission of this thesis, which to my knowledge

has reached the requisite standard.

The thesis or any part thereof, has not been

submitted to any other University or Institution for

the award of any Degree or Diploma.

(R.B. Chavan) Thesis Supervisor,

Department of Textile Technology, Indian Institute of Technology Delhi,

New Delhi 110016.

CURRICULUM VITAE

1970 , B. Tech (Text) in I Class, Madras University

1970-71 Supervisor, M/s Anglo French Textiles, Pondicherry.

1971-74 M. Tech. (Text) in I Class with Distinction

1971-74 Instructor, , Dept. of Textile Technology, A.C. College of Tech., Madras.

1974— Lecturer, onwards Dept. of Textile Technology,

A.C. College, Madras.

1979-82 Engaged in the present work.

k

AC KNOW WLEDGE EN TS

The "philosophy" that I learnt pursuing the

"Doctor of Philosophy" is that research is never a one man

act. Scores of people directly or indirectly were involved

in my research programme and, thank God, everyone had

facilitated me in my pursuit. I feel that I am lucky in

this respect and I bow to all of them, with a .;deep sense

of gratitude.

First and the foremost among them is my thesis

supervisor, Dr.. R.B. Chavan, Assistant Professor, Depart-

ment of Textile Technology, Indian Institute of Technology,

for his heuristic approach, for allowing complete freedom

of work, for initiating me into this "research culture" and

for warm heartedness.

To late Prof. S. Krishnamurthy and Perarignar Anna

University of Technology, Madras for having deputed me for

Ph.D Linder Quality Improvement Programme.

To Professor C.D. Shah, Head of Textile Technology

Department, Prof.. V.B. Gupta, Prof. (Miss) P. Bajaj and

Prof.. M. L. Gulrajani for their unfailing help in every

aspect, for providing all the facilities in the department

and for the valuable suggestions.

To Prof. S.R. Sivaraja Iyer, University Department

of Chemical Technology, Bombay, for the valuable discussions.

To Dr. Raj Kumar, ATIRA, Ahmedabad, Dr. S. Chopra and

Dr. H. Bohidhar, Department of Physics, I.I.T. Delhi and

Dr. A. Hussain,CMST, IIT Delhi, for helping in conducting

different experiments.

To all the technical staff of Textile Department,

for their ungrudging cooperation.

To my beloved parents and natural mother who always

prayed for me.

To my wife and sons, Shiva and Prasad who bore my

separation ungrudgingly and without distraction to my

research work.

To Mrs. and Mr. J.L. Bhatt and their children who

made me feel at home:during my three years stay in Delhi

and also for helping in the preparation of the manuscript.

To all my Shivalikites and research colleagues for

their never ending help.

To Mr. Rajesh K. Arora, for typing the manuscript

with speed and efficiency.

ii

A special word of thanks to my teacher,

Shri R.A. Quraishi, who was instrumental in inducting me

to this "research culture".

iii

(J. Venkata Rao)

ABSTRACT

An attempt was made to understand the dyeing mechanism

of water swollen-sovent exchanged (WSSE) cotton with anionic

dyes from dimethylformamide-trichloroethylene (DMF-TCE) sol-

vent mixtures. For this purpose three anionic dyes,

Naphthalene Red JS (CI Acid Red 88), Naphthalene Red EA

(CI Acid Red 13) and Naphthalene Scarlet 4R (CI Acid Red 18)

having the same structure but varying number of sulphonic

acid groups from 1 to 3 were selected. The dyeing of WSSE

cotton with anionic dyes was explained on the basis of the

electrokinetic character of cotton in the solvent medium,

analysis of adsorption isotherms, dyeing behaviour of oxidized

cotton and the use of solubility parameter concept. The

state of dye in solution was determined from the aggregation

behaviour of the dyes in DIIF-TCE solvent mixtures using a

new technique, namely, quasielastic light scattering.

SYNOPSIS

Water as a medium for chemical processing of textiles

is used universally. However, its use is not free from

problems such as effluent treatment, stream pollution and

high thermal energy required for evaporation. The use of

non-aqueous medium was therefore considered to be an alter-

native medium for chemical processing of textiles. Chlori-

nated hydrocarbons such as perchloroethylene, trichloro.-

c thylene, 1 ,1 ,1--trichloroethane etc. , were found to be more

suitable for this purpose on the basis of their non-inflamm-

ability, stability towards repeated recovery and low thermal

energy required for evaporation. Processes such as scouring

of natural And synthetic fibres have been commercialised

using these solvents. Considerable information is also

available on the dyeing of synthetic fibres such as

polyester with disperse dyes. This was possible because of

non ionic nature of the dyeing system. However dyeing of

natural fibres such as cotton with anionic dyes using

chlorinated hydrocarbons was not possible due to non-polar

nature of the solvents the fibre swelling was poor and the

anionic dyes were insoluble in such solvents. To overcome

these problems, it was essential to use a polar solvent

ii

like itiater or dimethyl formamide (DMF) at certain stage of

dyeing for fibre swelling and dye solubilization. Certain

systems have been reported in the literature based on the

above principle L-4,77 A more systematic study has been

reported by Chavan and Co-workers for the dyeing of cotton

with acid, direct and reactive dyes using polar and non-

polar solvent mixtures LT3-177. It was reported that a

reactive dye could successfully be exhausted and fixed on

cotton when the dyeing was carried out from dimethyl formaemide-

trichloroethylene (D AF-TCE) solvent mixture. This study is

of importance because hydrolysis of a reactive dye in aqueous

system is almost inevitable. If the presence of water in the

dye bath is reduced or elimin .ted, the dye hydrolysis could

be minimised or avoided leading to higher dye fixation on

cotton. Higher dye exhaustion and better fixation were

achieved when aqueous-alkaline -pre-swollen cotton wag dyed

in DMF-TCE solvent mixture 04,15, . acetone and the ,Mixtures

of acetone-TCE assisted by a small proportion of water or

DMP was also suggested for the application of reactive dyes

on water or aqueous-alkali-swollen cotton LT77. The work

on the application of acid and direct dyes on water swollen-

solvent exchanged (WSSE) cotton from DMF-TCE solvent mixture

revealed that with the increase in TOE content in the solvent

dye bath, the dye-uptake on the fibre was increased. This

iii

increase in dye uptake was attributed to "the decrease in dye

solubility in the solvent mixture. The present work is an

extension of the earlier study on the application of anionic

dyes on cotton from DMF-1E mixtures. For this purpose three

anionic dyes (CI _1A,cid Red 88, CI Acid Red 13 and CI Acid

Red 18) having the same structure but number of sulphonic

acid groups varying from 1 to 3 were specifically selected.

It was postulated that the transfer of the dye from external

phase to the internal liquid phase closely associated. with

the fibre (which was essentially DMF) takes place due to

solubility difference, followed by I ngmuir adsorption. The

above hypothesis was based on the experimental observations on

the electrokinetic character of cotton in the solvent mediui,

analysis of the adsorption isotherms and the dyeing behaviour

of oxidized cotton. An attempt was also made to 'explain the

dyeing observations on the basis of solubility parameter

concert. To understand the state of dye in solution the

aggregation behaviour of the dyes in DMF-TCE solvent

mixtures was also studied.

The thesis has been divided into seven chapters.

First chapter relates to the general introduction and a

review of literature.

In the second chapter the zeta potential existing at

the interface of W$SE cotton and DTMF,TCE and their mixtures

was determined using streaming potential technique, and its

effect on dyeing was discussed.

In chapter three, to understand the dyeing mechanism,

the equilibrium dyeings were carried out at 400C from I F-

TCE mixtures. The adsorption isotherms were constructed

and interpreted in terms of distribution of dye between the

dye bath and the solvent closely associated with the fibre

followed by Langmuir adsorption on cotton. Using Iangmuir

equation affinity values were calculated. It was observed

that the dye affinity increased with the increase in

aulphonic acid groups in dye molecule and also with the

increase of TCE content in the solvent mixture.

The study of equilibrium adsorption of the dyes on

oxidized cotton from DMF-TCE mixtures as reported in

chapter four revealed that at any IMF-TOE ratio the dye

uptake expressed in terms of percent exhaustion was decreased

with increase in carboxyl content. However, with the Increase

in TOE content in the solvent mixture the dye uptake was

increased. Although there was increase in dye uptake with

the increase in TCE content in the solvent mixture, for any

iv

particular dye, the repulsive effect of carboxyl groups,

as determined from the extent of reduction in dye uptake

was found to be almost same. This fact revealed that the

internal liquid closely associated with the fibre was

essentially DMF, from which dyeing takes place. The

reduction in dye uptake due to repulsive effect of carboxyl

groups varied with the number of suiphonic acid groups in

the dye niolee ule. It was noticed that the presence of

carboxyl groups changed the isotherm from Iangmuir to Sigmoid shape.

In chapter five some of the basic principles of solu-

bility parameter concept and its effect on dyeing behaviour

have been discussed. The solubility parameters of the dyes

were theoretically calculated by Van Krevelen's method.

The solubility parameters of cotton, DMF and TOE were taken

from literature. The solubility parameter of solvent

mixtures were calculated using standard equation. The solu-

bilities of dyes in DMF and DMF-WE mixtures and dyeing

behaviour of cotton from DMF-LE mixtures were related to

solubility parameter values. However, in order to explain

all the dyeing observations it was thought to be essential

to divide the total solubility parameter of cellulose ,dyes

and solvent mixtures into solubility parameter due to

v

association forces (CcA) and solubility parameter due to

dispersion forces (9d). The cd.-values were calculated

from refractive indices. The refractive indices of the

dyes were theoretically determined with the help of model

compounds using Lorentz and Lorenz equation. For solvent

mixtures the refractive indices were experimentally deter-

mined and the refractive index of cotton was taken from

literature. £-values were calculated using a standard

equation. The total picture on the dyeing behaviour of

cotton from solvent mixtures emerged from the above concept

revealed that the dye adsorption was mainly governed by dis-

persion forces. This fact was experimentally verified by

studying the effect of temperature on dye uptake. It was

observed that the temperature had no effect on dye uptake

which suggested that the adsorption process was mainly

governed by the weak attractive forces like dispersion

forces.

The sixth chapter deals with the aggregation behaviour

of the dyes in DMF-TOE solvent mixtures. For this purpose,

a new technique, namely, quasi-elastic light scattering (QI5)

was employed. It was observed that the aggregation tendency

vi

0

of the dyes in DMF- TE mixtures was dependent on the TOE

content and on the number of sulphonie acid groups and

their position in the dye molecule.

The salient features of the dyeing systems are

swnmarised in the concluding chapter.

vii

Page CONTENTS No.

ABSTRACT

SYNOPSIS

CHAPTER 1 GENERAL INTRODUCTION

1.1 Solvent Dyeing of Cotton

1.2 Solvent Exchange Technique and its Application. 9

CHAPTER 2 EI,ECTROKINETIC STUDY

2.1 Introduction 13

2.1.1 Electrokinetic phenomena 13

2.1.2 Electrokinetic studies on cotton 16

2.2 Materials 18

2.3 Experimental Methods 19

2.3.1 Streaming Potential Measurements 19

2.3.2 Viscosity and Density 21

2.3.3 Dyeing 21

2.4 Results and Discussion 21

CHAPTER 3 THERMO DYNAMICS OF DYEING

3.1 Introduction 25

3.1.1 Adsorption Isotherms 25

3.1.2 Thermodynamic treatment of adsorption isotherms. 25

3.1.3 Mechanism of dyeing of cellulosic fibres with anionic dyes in aqueous 30 system.

Page No.

3.2 Materials 37

3.3 Experimental Ii[ethods 37

.3.3.1 Preparation of Naphthalene Red EA 37

3.3.2 Purification of dyestuffs 38

3.3.3 Determination of dye purity 39

3.3.4 Dye solubility 40

3.3.5 Dyeing 41

3.3.6 Estimation of dye 42

3.4 Results and Discussion 42

3.4.1 Effect of solubility on dye uptake 42

3.4.2 Rate of dyeing 45

3.4.3 Analysis of adsorption isotherms 46

CHAPTER 4 DYEING OF OXIDIZED COTTON

4.1 Introduction 53

4.2 Experimental Methods 56

4.2.1 Preparation of oxidized cotton 56

4.2.2 Estimation of carboxyl groups 57

4.2.3 Dyeing 59

4.3 Results and Discussion 59

4.3.1 Effect of DMF-TCE ratio on dye uptake. 59

4.3.2 Effect of sulphonic acid groups on dye uptake 61

4.3.3 Adsorption Isotherms. 61

Page No.

CHAPTER 5 SOLUBIISTY 21)11L'IUMP,

5.1 Introduction 63

51.1 Solubility parameter 63

5.1.2 Determination of solubility parameter 63

5.1.2.1 Solvents 63

5,1,2,2 Solvent mixtures 67 5.1.2.3 Polymers 67

5.1,3 Three dimensional solubility parameter 71

5.1,3.1 Determination of individual components. 72

5.1.4 Application of solubility para- meter concept 75

5.1.4.1 Pigment dis-persion 75

5.1.4,2 Polymer and plasticizer compati- bility 76

5.1.4.3 Wettability of polymers 76

5.1.4.4 Gas-liquid solubility 77

5.1.4.5 Tensile strength 78

5.1.4.6 Dyeing 79 5.1.5 Limitation of solubility parameter

concept in dyeing 82

5.2 Experimental Methods : Determination of Solubility Parameter and its Components 83

5.2.1 Dyes 83

5.2.1.1 Total solubility parameter 83

5.2.1.2 Solubility parameter due to dispersion and association forces 83

Page No.

5.2.2 D14F, TOE and their mixtures 87

5.2.3 Cotton 87

5.3 Results and Discussion 88

5.3.1 Dye solubility in DMF and DMF-1E mixtures 88

5.3.2 Dye uptake from DMF-TCE mixtures 89

CHAPTER 6 AGGREGATION OF DYES IN SOLUTION

6.1 Introduction 93

6:.1.1 Determination of aggregation number 93

6.1.1.1 Conductivity measurements 93

6.1.1.2 Radiation induced processes 94

6.1.1.3 Diffusion measurements 97

6.1.1.4 Other methods 101

6.1.2 Reasons for aggregation 101

6.1.3 Aggregation behaviour of anionic dyes 10~

6.2 Experimental methods 107

6.2.1 Quas ie lastic light scattering study 107

6.2.2 Theory 108 6.2.3 Determination of the radius of

the aggregate and aggregation number 109

6.2.4 Instrumentation and experimental procedure 111

6.3 Results and Discussion 113

Page No.

CHAPTER 7 HOARY 118

REFERENCES

APPENDIX I

APPENDIX II

APPENDIX III

List of Research Publications and

Review Articles written.

i to xi