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Dyeing Effects Of Bifunctional Reactive DyesOn Knitted Cotton Fabrics

Introduction:

Several new bifunctional reactive

dyes of the Sumifix Supra range that

carry monochlorotriazine and sulphato

ethyl sulphone reactive systems were

developed and their dyeing perfor-mance studied. Suitable characteristic

properties and fastness properties were

examined over the knitted cotton fab-

rics. The dyes were characterized by

spectral data and elemental analysis.

The dyes structures were established

by preparing the coupling component

using H-acid, cyanuric chloride and 2-methoxy-5-methyl (sulphato ethyl) SUI-

phonyl aniline which was readily cou-

pled with various diazotized 2-amino

benzo-thiazole (Figure 1). The results

indicated good solubility, a high degree

of exhaustion and fixation, excellentfastness degree and higher substantivi-

ty over the knitted cotton fabrics.

While cotton fabric is an essential

element in today's world, reactive dyes

are needed to complete ready to wear

clothing requirements. With the intro-

duction of the three Procion dyes by ICI

for cellulosic fabric in 1956, the cova-

lent bonding of cellulosic fiber to the

reactive systems proved to be notewor-

thy. Further research on cotton goods

resulted in the eventual introduction of a

newly variable reactive system in reac-

tive dyes.'The term heterobifunctional dyes

became widespread after the 1980's

through the involvement of four dyes

containing monochloro-triazine masked

vinyl sulphone (VS/MCT) by Sumi-

tomo,2 which was later called Sumifix

Supra dyes. In 1959, I.C.I3 and, in

1961, Hoechst4 and a few other manu-

facturers claimed the development of

two different reactive groups, by intro-

ducing several dyes, yet none werecommercialized except one by Hoechst

By M.M. Dalal, K.R. Desai,

Dept. of Chemistry, South Guiarat Univ.,

Surat, India

Table I: Characterization and spectral data of compound Vlla-l.

in 1975.1 After 1980, the major dyestuff

manufacturers have applied for more

than 100 patents related to dyes withtwo or more different reactive groups.

This fact demonstrates the importanceof the bifunctional dyes in the field of

:search as a new generation of reac-

ve dyes.

Bifunctional dyes

Bifunctional dyes carry two reactive

groups. They are known for their excel-

lent dyeing efficiency and overall fast-

ness properties. Bifunctional dyes with

good dyeing properties are created by

the careful selection of the right reactive

groups and right chromophores. How-

ever, the concepts of dyes with two

reactive groups of the same type (e.g.

bis-sulphato ethyl sulphonyl and bis-tri-

azinyl types5) as well as a number of

less commercially successful elec-trophillic groups date back to the early

days of reactive dyes, and predates the

appearance of the first mixed reactive

system in the 1980's.6

A major advantage of MCT/VS, dyes

over the dyes containing either MCT or

VS reactive group is the higher degreeof fixation of the former and is 1.3 to 2.3

times more than the latter.' It can easily

be assessed that dyes with two identical

reactive groups and dyes with two dif-

ferent reactive groups exhibit a higher

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Figure 1: Reaction of ozone with indigo. were collected for studying the primary

secondary exhaustion and the percent

20 spectrometer.

fixation and relative fixation yield.

Exhaustion and fixation study

was studied by known methods, collect-

The dye-bath exhaustion and fixation

ing the samples of exhausted liquor at

various intervals and studying the

liquor up to various fold by known meth-absorbance by diluting the exhaust

ods on a Bausch and Lomb Spectronic-

SolubilityDue to the presence of the OH and

dihydrogen phosphate (0.83 g) in water formed at a goods to liquor ratio of 1:20cule, a dissociation resulted in a higher(2% O.W.f) in an exhaust process infollowed by sufficient sodium chloride

NH functional group in the dye mole-

solubility during the dyeing process at athree step dyeing by heating up to 60C(15.20 g) was added to precipitate theproduct. All organic impurities were then within 30 min with 50 g/liter NaCl and 5 low liquor ratio. Also, the presence of

extracted by washing with a small portion g/liter sodium carbonate. This tempera- the sulfonic chromophores (two to

of diethyl ether. All the compounds Vllb-1 ture was then held for 30 min, then

gradually 4 ml/liter of 32.5% sodiumwere prepared by the same method.

three) and the novel sulphatoethyl sul-

the new bifunctional (MCT/SES) dyes.hydroxide and 5 g/l NaHCO3 solutionThe characterization, elementalphone groups promoted the solubility of

analysis and spectral data's are fur-

nished in Table I of dyes Vlla-1 and the

Also, during the dyeing process7 nowas added so that the pH attained

highly soluble in the presence of com-ued for 45 min longer. The final dyeddyeing fastness properties are tabulat-

urea was required and the dye wasreached 11.5. The dyeing was contin-

ed in Tables II and Ill. pattern was rinsed with water for 5 min mon salt at a low liquor ratio.

Dyeing cotton Rf valuethe final rinse water was colorless.

(at 30C) and 10 min (at 60C) so that

The dyeing of cotton fabric was per- The Rf value of synthesized dyesThe samples of dye-bath exhaust

culated is shown in Table II.TLC chamber for 9h. The Rf value cal-

(4:3:3) at a room temperature of 28C in

sition 2-methyl propanol-butanol water

(1.0 mm thickness) and solvent compo-

chromatography system on Silica Gel G

was calculated through a thin layer

dyeing method was widely taken intoThe pH of dye-bath during exhaust

consideration. Here, we first used the

neutral pH and gradually increased toalkali by dosing the Na2CO3/NaOH to a

pH of 11.5 to differentiate the probable

exhaustion in both cases. Both SES and

MCT groups functioned as the reactive

sites. However, we recommend a dye-

ing process for this type of dye exhaust

dyeing method set at 60C with a con-trol dye-bath pH.

Color measurement

pH

The (%R) percent reflectance of the

dyed material was measured at different

culated using the Kubelka-Munk equa-

700 nm) using a ACS-600 color control

wavelengths in the visible region (400-

system. The K/S value at l max was cal-

tion K/S = (I-R)2/2R Table II.

Shade evaluation

The hue over the knitted cotton fabric

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Table II: Analytical data and dyeing performance of compound Vlla-j

Com- Primary Secondary Fixation Relative fix-pound Rf value exhaustion exhaustion yield ation yield

(%) (%) (%) (%)

Vlla 0.78 485 3.0 35 77 57 74

Vllb 0.68 495 4.8 38 69 61 88

Vllc 0.45 520 6.5 42 78 65 84

Vlld 0.80 490 8.2 56 75 62 82Vlle 0.73 505 7.8 40 79 61 77

Vllf 0.69 540 2.3 51 80 67 84

Vllg 0.76 575 4.6 44 78 66 85

Vllh 0.66 497 5.2 35 82 69 84

Vlli 0.72 575 7.2 47 85 65 76

Vlli 0.55 495 7.8 38 65 52 80

Vllk 0.83 556 3.2 49 78 49 63

VlIl 0.80 565 6.8 42 83 62 75

able 111: Color shade and fastness properties of compound Vlla-j.

Color of Light Wash

Rubbing

fastness

Dry Wet

Compoundcrystal

Shadefastness fastness

Brown black

Violet-black

Violet-black

Bluish black

Bluish black

Blue

Violet-black

Blue

Violet-black

Violet-black

Bluish blackBluish

Light brown

Red-violet

Brill.-violet

Brill. Blue

Blue-green

Blue

Brill. Blue

Violet

Blue

Red-violet

Blue-violetBrill. blue

6 5

5-6 5

6 5

6 5

6 4-5

5-6 5

6 5

6 5

6 5

5-6 5

6 56 5

55

5 5

55

.5 5

55

55

55

55

55

5 4-5

5 555

as checked by matching it with stan-

dard shade cards. The resultant variation

the hues had occurred since the sub-situent offers the bathochromic shift

good penetration and higher depth.The

shade appeared at a somewhat higher

wavelegth of the dye, having sub-ituent at 6th and 4th and 6th position.

Fastness test

Fastness to light was assessed on a

Fadeometer in accordance with BS:

1006-1978, The wash fastness test in a

Launderometer in accordance with IS:

765-1979 and the rubbing fastness on

Crockmeter (Atlas) in accordance with

AATCC-1961.

Substantivity

The dyes showed medium-to-good

substantivity which can be detected by

the exhaustion and fixation study. This

can be due also to the presence of the

American Dyestuff Reporter c April 1996

two precursor (MCT-SES) groups as the

reactive sites involved in the dye sub-

strate. The substantivity of the hy

drolyzed byproduct can be readily detect-

ed from the amount ofunfixed dye and

can easily be removed after three or four

washes at different temperatures.

Chemistry

The bifunctional dyes containin!

MCT/SES system has been synthesizec

The reactivity of the dye can be sea

through the amount of the dye fixed over

the fiber. The probable attachment site:

increases due to the presence of two

reactive groups, MCT and vinyl SUlphone

(precursor of -sulphatoethyl sulphone)

The amount of the dye exhaust over the

fiber through primary exhaustion (neu

tral) appears to be somewhat medium

However, it has been relatively

increased as can be seen from the data

of secondary exhaustion (alkaline pH

Table II). The fixation yields range

between 60 to 70% except for the dye

VIIj and VIIk whose yield is significantly

lowered. However, the dye Vllh appears

to have a higher yield.

The relative fixation yield is higher

than 70% for all dyes except dye Vllk

(6346). However, the poor absolute yield

may relate to its low substantivity. In

general, the neutral exhaustion varies

from dye to dye. It does not at all affect

the secondary exhaustion % which can

be evidenced by compiled data. Overall,

values cannot be compared due to the

several changes the appeared during

the dyeing at pH 7 to pH 11.5. The study

shows that due to the presence of the

two reactive sites the probable attach-ment may be increased over the sub-

strate which allows one to conclude thatthe bireactivity is fully utilized.

The presence of the electron with-

drawing substituents increase the fad-ing rate. Also, the dyes having sub-stituent at 4th position also show some

ow-light fastness. However, the overall

light fastness of all dyes appears to be

good. However, in the case of wash

fastness excellent results are seen. The

amount of the hydrolyzed dye having

low substantivity released easily from

he substrate after two to three washes.

Also, the higher molecular size greatly

increased the wash fastness. The rub-

bing fastness also appeared to be good

due to the presence of the electron with-

drawing substituent which shows thebathochromic effect at an increased

wavelength in the case of shade [hve].

Overall, the presence of the two

reactive systems (MCT/SES) in dyesVLLa-1 shows good reactivity with high

degree of fixation, increased substantiv-

ty color strength (K/S value of dye fab-

ric), high fastness levels and excellent

wash-off over knitted cotton fabrics.

c c c

References(1) Zollinger, H. (1991) : Text Chem

Colorist, 23(12), 19.(2) Fujioka, S., Abeta, S. (1982) : Dyes &

Pigrnents. 3, 281.(3) Barker, P., Hunter, J., ICl (1959) : B.P.

101434.(4) Boedecker, H. (1961) : U.S.P.

3,223,470.(5) Cassella, C. (1959): G.P.: p. 1794297;

1991) C.A.: 58, 43253.(6) Seigel, E.; In The Chemistry Of Syn

dyes. Ed : Venkatrarnan K., Vol. 6, N.Y., AcadPress.7) Matsui, M., Meyer, U., Zollinger, H.

1988) : JSDC, 104, 425.(8) Luttringer, J., Ciba-Geigy (1993) :Text

Chem Colorist, 25(5), 25.(9) Vashi, H., Desai, K. (1995) : AmDyestuffReporter, March, 52.

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