394 JSDC NOVEMBER 1972; SUBRAMANIAN AND TARAPOREWALA

Mr DERBYSHIRE: An answer to this question could only come from data on the effect of the different auxiliaries tested on the aqueous solubility of the dyes. Some work is in hand to try to obtain information of this kind, which we believe is essential to achieving a better insight into the mechanism of the levelling action of carriers.

Dr D. G. DUFF: In general, are the best levelling carriers the least effective for carrier dyeing at the boil, and, if so, does the

form of Tumescal D, modified for improved levelling, give a less efficient carrier than the old form?

Mr DERBYSHIRE: AS pointed out in the paper, some of the better levelling carriers under HT conditions are relatively in- effective for increasing yield at the boil, and the converse is true for other carriers. Diphenyl, however, appears to be effective in both respects. The improved formulation of diphenyl (Atexal CA-DP) is of higher effectiveness in both HT levelling and carrier dyeing at the boil compared with Tumescal D.

Co m m u n ica t io ns Identification of Application Classes of Dyes on Man-made Fibres

R. V. R. SUBRAMANIAN AND K. S. TARAPOREWALA

The Silk & Art Silk Mills’ Research Association, ‘Sasmira’, Dr Annie Besant Road, Worli, Bombay-25DD, India

A scheme for the rapid identification of the application class of dyes on man-made fibres is presented. This scheme obviates the need to identify the classes of fibres present in a sample, except with regard to protein fibres, as well as the need to identify the dyes present

on each class of fibre separately.

Introduction The development of man-made fibres has made rapid progress

in recent years. Thus, viscose rayon (normal and modified types), secondary cellulose acetate, cellulose triacetate, nylon, polyester. polyolefins, poly(viny1 alcohol), polyacrylonitrile, poly(viny1 chloride), polyurethanes, etc., are all produced commercially. The development of new dyes for these fibres has necessitated the formulation of methods for identifying them.

Earlier schemes of dye identification, e.g. Green’s tables (I), giving a systematic identification of dyes on vegetable and animal fibres based on both application and chemical class, are well known. These tables were modified and extended by Clayton (2) in 1946. Since then several further schemes have been pub- lished, notably those of Bode (3) and Koch (4) dealing with the German methods, a review of American methods given by the New York Section of the AATCC (5) and that of Giles et al. (6). A useful discussion of various methods of identification has been given by Garner (7).

Most of these schemes of dye identification describe systematic methods. However, for a practical dyer or a laboratory technician, rapid identification of the class of dyes present on a dyed textile material is imperative. Thus, an identification scheme was formulated by Salvin et al. (8) in which, as in earlier systems, identification of the fibres present is necessary before the relevant test methods are applied. It will be appreciated that such a system of identification will be time-consuming and will therefore defeat the underlying purpose of a rapid method of identification. Further, once the fibres present in the material under examination have been identified individual identification schemes for dyes on each of the fibres present have to be followed, which again will take a considerable amount of time. Moreover, many of the reagents specified in this scheme are not normally available in a textile laboratory, especially in the developing countries.

A scheme (p. 396) has therefore been formulated wherein the need to identify the fibres present before identifying the dyes has been obviated. Thus, there is a considerable saving in time. Since this scheme is applicable to viscose rayon fibres also, it can be extended to natural cellulosic fibres such as cotton and jute. The need to identify the fibres present in the sample is limited to protein fibres such as wool, silk and casein. Finally the present scheme makes use of comparatively inexpensive chemicals generally available in all textile units and laboratories, and thus offers some savings in cost as well.

Although the methods given here are the results of tests carried out on a large number of dyeing and prints, they cannot be regarded as perfect in every detail. It should be emphasised that this scheme offers only a rapid method of identification of application classes of dyes present on man-made fibres and hence, for a systematic identification of the dyes, the various schemes mentioned above should be referred to.

Equipment 1, Microscope 2. Porcelain crucible 3. Separating funnels 4. Test tubes

Materials 1. Lead acetate paper 2. Wool mordanted with potassium dichromate and sulphuric acid 3. Scoured secondary cellulose acetate fabric 4. Scoured cotton fabric 5. Scoured wool fabric

Reagents 1 . 5% Acetic acid ( 5 nil sp. gr. 1 .OS/ 100 ml) 2. 1% Ammonia solution (10 ml sp. gr. 0.880/1) 3. Carbazol 4. Diethyl ether (solvent) 5. Ethylenediamine hydrate {sp. gr. 0,960) 6. Ethylenediamine tetra-acetic acid, disodiuiii salt 7. Formic acid (85%) (sp. gr. I .20) 8. Formosul G 9. Glycerol

10. 16% Hydrochloric acid (16 ml sp. gr. 1 * l8/lOO mi) 1 I . Hydrochloric acid (conc.) (sp. gr. I .18) 12. Hydrogen peroxide (100 vol.) 13. Hypochlorite solution (dilute) (0.276 available chlorine) 14. Magnesium ribbon 15. Nitric acid (conc.) (sp. gr. 1.42) 16. 1% Solution of non-ionic detergent [e.g. Lissapol N (TCI)] 17. o-Chlorophenol 18. Liquid paraffin 19. Potassium ferrocyanide 20. Pyridine:water (57:43) (vol./vol.) 21. Sodium acetate 22. Sodium carbonate 23. 5% Sodium hydroxide solution 24. 20% Sodium hydroxide solution 25. Sodium dithionite 26. Sodium nitrate 27. 10% Solution of a dispersing agent [e.g. Dispersol AC (ICI)]

IDENTIFICATION OF DYES ON MAN-MADE FIBRES 395

28. 5% Sulphuric acid (5 rnl sp. gr. 1.80/100 ml) 29. 1 % Tannic acid solution 30. Toluene 31. Zinc dust (pure) 32. Dioxan

Preparation of Specimens for Dye Identification Since the dyed or printed textile materials are likely to contain

various types of finishes, these should be removed before pro- ceeding with dye identification.

The following procedure is given as a guide, although it must be stressed that it is likely that a number of finishes will be encountered which will not be removed by the treatments described and for which certain other treatments may be neces- sary:

1. Scour the specimen with 1 g/1 of a non-ionic detergent at 60-70°C for 15-20 min. Wash well with warm water, followed by cold water, and dry. This treatment will remove most of the loosely held dyes.

2. If acrylic, methacrylic or styrene resins are present, treat the specimen under reflux with a mixture of dioxan and water (1050 or 1O:lOO) for about 2-3 h ; wash with water and dry.

3. If urea-formaldehyde or melamineformaldehyde resin is present, treat the specimen with 1 % hydrochloric acid at 70-80°C for about 15-20 min, then wash well with hot water, 0.1% ammonia solution and cold water respectively and dry.

If treatments 2 and 3 are to be used, treatment 2 should precede treatment 3.

Note-It should be noted that in the dioxan treatment, azoic, certain azo dyes (direct dyes, diazotised and developed, and developed disperse dyes) and vat dyes are likely to be extracted.

Hence, if the dioxan extract is coloured, it should be tested for the presence of such dyes by the following method:

Take 10 ml of the dioxan extract and add to it 2-5 ml of 20% sodium hydroxide and 5-10 mg of Formosul G and boil for 5-10 min. Note any change in colour. Then add to it 1-2 ml of 100-vol. hydrogen peroxide. If the original colour of the solution is now restored, it indicates vat dye. (The exceptions are with certain blue vat dyes, the leuco compounds of which are also blue.) If not, it indicates azoic or certain diazotisable azo dyes (direct dyes, diazotised and developed, and developed disperse dyes).

* * * We thank Mr 5. G. Parikh for his keen interest and encourage-

ment in the present work, Mr s. D. Deshpande and Mr A. Sardana for assistance with the experimental work, and members of TDC 38:l and TDC 38 of the Indian Standards Institution for helpful suggestions. (MS. received 7 December 1971; revised MS. received 27 March 1972)

References 1 Green, ‘The Analysis of Dyestuffs’ (London: Griffin & Co. Ltd,

1915). 2 Clayton, ‘Identification of Dyes on Textile Fibres and Detection of

Metals in Fibrous Materials, Dyes and Organic Pigments’ (Bradford: The Society of Dyers and Colourists, 2nd edn, 1946).

3 Bode, Mellimd Textilber., 41 (1960) 34. 4 Koch, ‘Rezeptbuch fur Faserstoff Laboratorien’ (Berlin: Springer-

Verlag, 1960). 5 AATCC New York Section, Amer. Dyestuff Rep., 47 (1958) 9. 6 Giles, Bashir, Dandekar and McKay, J.S.D.C., 78 (1962) 125. 7 Garner, ‘Textile Laboratory Manual’ (London : Heywood Books,

8 Salvin et at,, Amer. Dyestuff Rep., 57 (1968) 817. 3rd edn, 1967).

(The Tables to this paper are printed on pages 396 and 397)

Iden

tific

atio

n of

AD

Dka

tiOn

Cla

sses

of D

yes o

n M

an-m

ade F

ibre

s

Azo

ic a

nd c

erta

in

dim

tisa

ble

azo

dyes

. T

reat

0.5

g o

f fre

sh

sam

ple

for

1-2

min

with

5

ml o

f bo

iling

pyr

idin

e.

Prof

use

blee

ding

of

colo

ur

-Azo

ic

Dye

. Slig

ht

blee

ding

of

colo

ur-

Dev

eloD

ed D

ispe

rse

Dye

.

Exam

ine

the

test

spe

cim

en u

nder

the

mic

rosc

ope.

Par

ticle

s of

dye

are

pre

sent

on

the

surf

ace

of th

e fib

re-P

igm

ents

(nam

ely

carb

on b

lack

, vat

, azo

ic o

r pht

halo

cyan

ine)

Aci

d D

yes,

Bas

ic (o

r ‘M

odifi

ed’ B

asic

) Dye

s, D

irec

t D

yes

and

Rea

ctiv

e D

yes

Trea

t 0.5

g o

f sa

mpl

e fo

r 1

min

in b

oilin

g l”

/b am

mon

ia s

olut

ion

Rea

ctiv

e dy

es. T

reat

a

fres

h sa

mpl

e fo

r 15

rnin

un

der

reflu

x w

ith 1

ml o

f co

nc. s

ulph

uric

aci

d di

lute

d to

a li

tre w

ith

wat

er a

nd 2

g/1

of

sodi

um

sulp

hate

. Dye

ble

eds i

nto

solu

tion.

A

dd s

cour

ed

woo

l. W

ool i

s st

aine

d-

A c

onsi

dera

ble

amou

nt o

f dy

e bl

eeds

into

sol

utio

n.

Dis

card

the

sam

ple.

A

cidi

fy th

e so

lutio

n w

ith

30%

ace

tic a

cid.

A

dd 0

.5 g

of s

cour

ed

woo

l and

dye

for

5-10

rn

in a

t 80-90°C. W

ool i

s dy

ed-A

cid

Dye

.

Trea

t a fr

esh

sam

ple

for

30 s

with

boi

ling

16%

hy

droc

hlor

ic a

cid.

Coo

l an

d ad

d 3

mg

of m

agne

sium

ribb

on o

r pu

re z

inc

dust

and

war

m

for 2

-3

min

. Pla

ce a

lead

ac

etat

e pa

per

on th

e m

outh

of

the

test

tube

.

Littl

e or

no

dye

blee

ds in

to so

lutio

n. T

reat

0-5

g of

fre

sh sa

mpl

e fo

r 1 m

in w

ith b

oilin

g 50

/, ac

etic

acid

.

Trea

t a fr

esh

sam

ple

with

co

ld d

ilute

hyp

ochl

orite

so

lutio

n fo

r 5-

10 m

in.

The

sam

ple

is e

ither

de

colo

rised

or i

ts c

olou

r lig

hter

in to

ne-

Ant

hraq

ubon

e R

eact

ive

Dye

. No

chan

ge in

co

lour

-Vat

D

ye. (

With

The

solu

tion

is d

istin

ctly

co

lour

ed. D

ivid

e th

e so

lutio

n in

to tw

o pa

rts:

(i

) To

one

part

add

ta

nnic

aci

d. F

orm

atio

n of

pre

cipi

tate

-Bas

ic

or ‘

Mod

ified

’ Bas

ic

Dye

. (i

i) T

o th

e ot

her

add

scou

red

woo

l and

w

arm

for

4-5

m

in;

stai

ning

of

woo

l- B

asic

or

‘Mod

ified

’ B

asic

Dye

.

2 gl

jl of

a n

on-i

onic

de

terg

ent a

t 85

-90°

C.

Dis

card

the

sam

ple;

then

ad

d 0.

5 g

of s

cour

ed

cotto

n to

the

zolu

tion

The

sol

utio

n is

not c

olou

red.

Tr

eat

0.5

g of

fre

sh s

ampl

e fo

r 1-

2 rnin

with

boi

ling

50/,

sodi

um h

ydro

xide

sol

utio

n.

Con

side

rabl

e am

ount

of

dye

is s

tripp

ed.

Div

ide

the

solu

tion

into

two

parts

: (i

) T

o on

e pa

rt a

dd s

cour

ed c

otto

n an

d w

arm

for

5-1

0 m

in. D

eep

stai

ning

-Dire

ct

Dye

. Litt

le o

r no

stai

ning

-Rea

ctiv

e D

ye.

deco

loris

ed a

nd o

rigin

al c

olou

r is

not

res

tore

d by

pe

roxi

de. D

irect

Dye

is c

onfir

med

. (N

on-d

isch

arge

able

dire

ct d

yes w

ill n

ot re

spon

d to

this

trea

tmen

t).

(ii)

To

the

othe

r ad

d Fo

rmos

ul G

. The

sol

utio

n is

No

blee

ding

of c

olou

r-

Rea

ctiv

e D

ye (o

ther

than

he

tero

cycl

ic h

alog

enat

ed).

Dire

ct dyes

afte

rtrea

ted

with

for

mal

dehy

de.

War

m 0

3 5 g

of

sam

ple

in

5%

sulp

huric

aci

d. A

llow

it

to co

ol. D

isca

rd t

he

sam

ple.

The

n ad

d 0.1 %

of

Car

bazo

le d

isso

lved

in

conc

entra

ted

sulp

huri

c ac

id to

this

ext

ract

, dro

p by

dr

op, w

hen

the

form

atio

n of

a b

lue

prec

ipita

te

indi

cate

s th

e pr

esen

ce o

f fo

rmal

dehy

de.

Dir

ect d

yes a

fter

trea

ted

with

cop

per,

chro

miu

m,

or n

icke

l. Ta

ke 1

ml o

f 10

0-vo

l. hy

drog

en p

erox

ide

in a

w

atch

glass a

nd a

dd

2-3

drop

s of

con

cent

rate

d am

mon

ia s

olut

ion

(0-8

80

sp. gr.)

. A

fter t

he ev

olut

ion

of b

ubbl

es h

as c

ease

d,

add

abou

t 0.1

g o

f sa

mpl

e. If

any

vig

orou

s ac

tion

is o

bser

ved,

it

indi

cate

s th

e pr

esen

ce o

f co

pper

, chr

omiu

m o

r ni

ckel

.

Not

e-D

irec

t dy

es lr

eote

d w

ith resin: T

hese

dye

s would be

iden

tifie

d by th

e tre

atm

ent g

iven

in th

e Tab

le, s

ince

the r

esin

pre

sent

wou

ld h

ave been removed

in th

e tre

atm

ent g

iven

for p

repa

ratio

n of

the

sam

ple f

or id

entif

icat

ion.

~

~ ~~

~ ~~

~ ~~

Vat

Dye

s, S

ulph

ur D

yes,

Rea

ctiv

e D

yes,

Ani

line

Bla

ck, A

zoic

Dye

s, D

irec

t D

yes,

Dev

elop

ed D

ispe

rse

Dye

s an

d C

hrom

e D

yes

Trea

t 0.5

g of

sam

ple

for 2

min

with

5-1

0 m

l of

boili

ng 2

0% s

odiu

m h

ydro

xide

sol

utio

n. A

dd 4

-5

ml o

f wat

er a

nd 1

5-35

mg

of s

odiu

m d

ithio

nite

and

boi

l for

1 m

in.

The

colo

ur o

f th

e sa

mpl

e re

adily

bec

omes

bro

wn

and

is re

stor

ed t

o bl

ack

whe

n ex

pose

d to

. .

atm

osph

ere-

Adm

e B

lack

.

War

m t

he s

ampl

e w

ith

conc

entr

ated

sul

phur

ic

acid

for

few

seco

nds

and

pour

the

liqu

id in

to

little

col

d w

ater

; a d

ull

gree

n co

lour

is p

rodu

ced.

A

nilin

e B

lack

is

conf

irmed

. Tr

eat

sam

ule 0

.5

for g

2-3 of

‘fre

sh

min

with

-

I $;$&

%ha

logen

ated).

No

colo

ur c

hang

e-

Chr

ome

Dye

. War

m

the

sam

ple f

or 1

-2 m

in

with

16%

hydr

ochl

oric

ac

id. C

ool a

nd a

dd

pyrid

ine-

wat

er (

57:4

3).

Dye

ble

eds i

nto

solu

tion.

Add

woo

l m

orda

nted

with

po

tass

ium

dic

hrom

ate

to th

is e

xtra

ct a

nd

war

m f

or 2

-3

min

. W

ool i

s dy

ed-

Chr

ome

Dye

.

c

cn 0 0 P 0

2-3

m. t

otto

n IS

st

aine

d-D

irect

D

ye

(Dii

tise

d and

Dev

elop

ed).

No

stai

ning

of

the

cot

ton-

Dev

elop

ed

Disperse D

ye.

I I

I

Solu

ble

Dis

pers

e D

yes,

Met

al-c

ompl

ex D

yes

and

Dis

pers

e D

yes

I A

sh T

est

Tre

at 0

.5 g

of s

ampl

e for

5-

10 m

in i

n co

ld

pyrid

ins-

wat

er (

57 :4

3)

Liq

uor i

s st

aine

d-

Solu

ble

Dis

pers

e D

ye.

Dis

solv

e 4

g of

eth

ylen

e-

diam

ine

tetr

a-ac

etic

acid

, di

sodi

um s

alt i

n 10

0 g

of

glyc

erol

. Hea

t the

sam

ple

in th

is m

ixtu

re a

t 14

0°C

.

Tre

at 0

.5 g

of

sam

ple

for

5 m

in w

ith b

oilin

g 5%

ace

tic a

cid.

If

som

e dy

e is

str

ippe

d,

cool

, add

die

thyl

eth

er

and

shak

e w

ell.

Eth

er

laye

r is

colo

ured

- D

ispe

rse

Dye

. T

reat

a fr

esh

sam

ple

in

hot l

iqui

d pa

raff

in a

t 16

0°C

for

5 m

in. I

f th

e dy

e is

str

ippe

d, a

dd

scou

red

acet

ate

fabr

ic.

Tin

ting

of a

ceta

te fa

bric

(i) W

ith L

ogw

ood,

the

pyri

dine

wat

er e

xtra

ct

is co

lour

ed dark

cher

ry-r

ed. O

n ad

ditio

n of

1-2

ml o

f co

nc. h

ydro

chlo

ric

acid

it tu

rns

yello

w

brow

n; f

urth

er, w

hen

shak

en w

ith to

luen

e,

dye

rem

ains

in w

ater

la

yer.

Ash

0.2

-0-3

g o

f sa

mpl

e in

a p

orce

lain

cru

cibl

e. A

dd 0

.2-0

-3 g

of

flux

com

pose

d of

eq

ual p

arts

by

wei

ght o

f po

wde

red

sodi

um c

arbo

nate

and

sodi

um n

itrat

e. F

use

the

mix

ture

an

d al

low

it to

cool.

Not

e th

e pr

esen

ce o

f an

y m

etal

s as in

dica

ted

belo

w:

(ii)

With

chr

ome

dyes

w

ater

laye

r is c

olou

red ;

bu

t som

etim

es to

luen

e la

yer i

s als

o st

aine

d to

a d

iffer

ent

colo

ur th

an

orig

inal

dye

ing.

chro

miu

m

Cob

alt

Cop

per

Man

gane

se

Nic

kel

Yel

low

R

oyal

Blu

e Fa

int B

lue-

Gre

en

Blu

ffir

een

Bro

wn

Pres

ence

of c

obal

t or m

anga

nese

- N

eutr

aldy

eing

1 : 2

Met

al-c

ompl

ex D

ye.

Pres

ence

of

chro

miu

m-D

irect

D

ye

(aft

ertr

eate

d w

ith c

hrom

ium

sal

t), C

hrom

e D

ve o

r Met

allis

ed D

ve (i

.e. 1

:1 a

nd

-Disp

erse

D

ye.

Ext

ract

ion

Test

Ext

ract

0.5

g of

sam

ple w

ith 1

5 ml o

f py

ridin

e-w

ater

(57

:43)

in

a te

st tu

be by

kee

ping

it in

a b

eake

r of b

oilin

g w

ater

for 1

0-15

min

, or

unt

il su

ffic

ient

am

ount

of

dye

blee

ds in

to th

e re

agen

t. D

isca

rd th

e sa

mpl

e an

d no

te th

e colour o

f th

e ex

trac

t. Po

ur th

e so

lutio

n in

to a

sep

arat

ing

funn

el a

nd a

dd 1

5 ml o

f to

luen

e; s

hake

well

and

allo

w th

e tw

o la

yers

to

sepa

rate

. The

dis

trib

utio

n of

dye

s be

twee

n th

e tw

o la

yers

is as

follo

ws:

Tolu

ene L

ayer

A

ll di

sper

se d

yes

Som

e ne

utra

ldye

ing

met

allis

ed d

yes

(1 :2

met

al-c

ompl

ex d

yes)

So

me

vat

dyes

So

me

reac

tive

disp

erse

dye

s A

ll az

oic

com

bina

tions

~~

Tolu

ene L

ayer

If

tolu

ene

laye

r is coloured, w

ash

it w

ith w

ater

thric

e.

Sepa

rate

the

tolu

ene

laye

r aga

in a

nd e

vapo

rate

it. D

ispe

rse

the

resi

due

with

a fe

w d

rops

of

a 10

% so

lutio

n of

a

disp

ersi

ng a

gent

in w

ater

. Add

sco

ured

woo

l and

ace

tate

to

this

ext

ract

and

war

m f

or 1

5 m

in

Onl

y w

ool i

s dye

d-

If bo

th w

ool a

nd a

ceta

te

Neu

tral

dyei

ng

are

dyed

-Disp

erse

D

ye.

Met

allis

ed D

ye (i

.e. 1

:2

Met

alco

mpl

ex D

ye).

Wat

er L

ayer

A

ll di

rect

dye

s AU b

asic

dye

s A

ll ac

iddy

eing

met

allis

ed d

yes

All

chro

me

dyes

AU a

cid

dyes

Lo

gwoo

d So

me

neut

rald

yein

g m

etal

lised

dye

s

(1 :1

met

alco

mpl

ex d

yes)

(1 :2

met

alco

mpl

ex d

yes)

1 :2

Met

al-c

ompl

ex d

yes’.

) Pr

esen

ce o

f cop

per o

r ni

ckel

- D

irec

t Dye

(aft

ertr

eate

d w

ith c

oppe

r sal

t or

nic

kel s

alt r

espe

ctiv

ely)

Misc

ellu

neou

s Tes

ts

Rea

ctiv

e Disperse Dy

es on

Nyl

on 6

and

6.6:

Dis

solv

e 0.

5 g

of

sam

ple

in 8

5% fo

rmic

acid

or

ochl

orop

heno

l and

pou

r th

e re

sulti

ng

solu

tion

into

1 m

l of

ethy

lene

diam

ine

hydr

ate

dilu

ted

with

5-1

0 ml

of

wat

er.

War

m fo

r 5-

10 m

in a

nd th

en fi

lter.

Dye

re

mai

ns w

ith th

e pr

ecip

itate

- R

eact

ive

Dis

pers

e D

ye.

If pi

gmen

ts are f

ound

to b

e pr

esen

t by

the m

icro

scop

e tes

t and

azo

ican

d va

t pi

gmen

ts a

re fo

und

to b

e ab

sent

by

the

rele

vant

test

s, th

en th

e pi

gmen

t pr

esen

t may

bee

ither

carb

on b

lack

or o

f th

e pht

halo

cyan

ine t

ype.

With

car

bon

blac

k th

ere w

ill be

no

disc

olor

atio

n whe

n th

e sa

mpl

e is

trea

ted

with

sod

ium

hy

drox

ide

and

sodi

um d

ithio

nite

. If

phth

aloc

yani

ne pi

gmen

t is p

rese

nt,

spot

ting

the

sam

ple

with

con

cent

rate

d ni

tric

aci

d w

ill p

rodu

ce a

brig

ht

gree

n to

ne.

Pigm

ents