Indian Journal of Textile· Research

Vol. 9. December 1984. pp. 1.35-138

Lightfastness of Reactive Dyes on Cellophane Dyed from Aqueous and N on­Aqueous Mediums

R B CHA VAN & A SUBRAMANIAN

Department of Textile Technology, Indian Institute of Technology, New Delhi 110016

Received Id October 1983; accepted 11 July 1984

~ An attempt has been made to study the state and lightfastness of thJl:e reactive dyes on normal cellophane and cellophanetreated with sodium zincate solution, the dyeing being carried out by using water, wa'ter-acetone, formamide-acetone andDMSO-acetone mediums, All the three dyes were found to be present in ~e aggregated form on both the films. The extent ofaggregation as measured from yjx ratio of the spectra of dyes was found to be in the order: water > water-acetone >formam ide-acetone ;;. DMSO-acetone, The lightfastness of dyes as indicated by characteristic fading curves also followed theabove order. The dyeings on cellophane treated with sodium zincate showed higher lightfastness, which was attributed to

better dye penetration due to the elimination of skin structure. ~

The lightfastness of different classes of dyes on textilematerials and their mechanisms have been reviewed byseveral workers 1 -3. I t has been suggested by manyworkers that the stronger the bond formed between thedye and the fibre, the greater the lightfastness of thedyeing4 -7. This has been attributed to the transfer of

excitation energy from the dye molecule to themacromolecule of the fibre. However, the reactive dyeshave the firmest dye-fibre bond, and their lightfastnessgradings are not higher than those of other fast dyes oncellulose.

Krichevskii and Vachobov8 found, from the rate of

fading of adsorbed and covalently bonded reactivedyeings on cellulose, that the nature of dye-substratebond does not materially affect the lightfastness ofreactive dyes.

Giles and coworkers9 ~16 emphasized that lightfast­ness in a hydrophilic substrate is largely governed bythe physical form of the dye and that dyes of highlightfastness are likely to be more highly aggregatedthan those of low lightfastness. This finding has beenconfirmed by Weissbein and Coven 17 from electronmicrograph studies.

Hildebrand 18 and Pisarvskanya ef al.19 also

observed that pot only the physical form but thechemical structure of the basic chromophore is alsoimportant in fading rate.

Kissa 20-21 observed that electrolytes and dyeingmethods affect the lightfastness of reactive dyes,lightfastness being higher for the process whichfavoured dye penetration. AA TCC Delaware Valleysection22 and Silver23 reported no change in thelightfastness of direct and reactive dyes when thedyeings were carried out using compatible mixtures of

solvent or water-solvent emulsion systems. Bose24noted a slightly inferior lightfastness of reactive dyeson cotton dyed using dimethylformamide-trichloro­ethylene solvent mixtures. In our earlier paper25 thelow dye uptake of viscose rayon as compared to cottonwhen the dyeings were carried out using water-acetone

mixture was attributed to the presence of highlyoriented skin structure in viscose rayon which offersresistance to dye penetration. Treatment of viscoserayon with sodium zincate suitably modified the skinstructure and increased the dye uptake and dyefixation equivalent to that on cotton25 . In the presentpaper, an attempt has been made to study the state andthe lightfastness of three reactive dyes On cellophane aswell as treated cellophane (sodium zincate 15% v/v)dyed with reactive dyes using water, water-acetone,formamide-acetone and DMSO-acetone mediums.

Materials and Methods

Three reactive dyes, viz. c.1. Reactive Red 31

(Procion Red H 8B), Orange 13 (Procion Orange H 2R)and Blue 5 (Procion Blue HGR), were used afterpurificat'ion by the solvent-nonsolvent method26 . Thecellophane film (25 11m thick) was boiled for half anhour with I g/litre Lissapol N, washed free from thedetergent and dried at room temperature.

Sodium zincate solution was prepared by thestandard method27. The cellophane film waspretreated with sodium zincate (15% v/v) at roomtemperature for 15 min. The film was washed and air­dried.

Fading experiments were carried out on alightfastness tester by using 500 W mercury-tungstenfluorescent lamp (MBTF)28. The absorption spectra

135

INDIAN J. TEXT. RES., VOL. 9, DECEMBER 1984

400

500

500

1600

,-fnm)

600

I700

06

700

0.5

~ 0.4

VlzU.J0--J

< 0.3w f-a.a

0.7

0.6

>-

o 5"" Vl

Zw0)04

0.30.20.1

0.6

confirmed from the fading rate curves of c.I. ReactiveRed 31 and Orange 13 on cellophane (Figs 5 and 6),which showed that the initial fading rate was higher,the fading proceeding later at a steady-rate, whichimplied that the initial fading was due to the fading of

II ( nm J

Fig. 2- Absopriton spectra of Orange 13 on treated cellophane dyedin different mediums [(a) water, (b) water-acetone. (c) formamide­

acetone. and (d) OM SO-acetone]

Fig. 3- Absorption spectra of Blue 5 on treated cellophane dyed in

different mediums [(a) water, (b) water-acetone, (c) formamide­acetone and (d) OMSO-acetone]

400500600700

05

0.4.

>-

~VlZ 0.3:w 0)~«~ 0.2 "

;:::0..0

0.1

of unexposed as well as exposed films were scannedwith a Beckmann DK2A spectrophotometer.

Films were pre~swollen with aqueous Na2C03solutioh (10-50 gjlitre) and centrifuged before dyeing.Dyeing was carried out in a Beaker dyeing machine(liquor ratio 100: I). Dye-bath exhaustion was carriedout at 25°C for I hr and fixation at 60°C for I hr. The

dyed samples were soaped at boil, thoroughly washedand dried at room temperature. The aqueous dyeingexperiments were carried out at 80"C using NaCl (60gjlitre) and Na2C03 (10 gjlitre)29.

Results and DiscussiolJ

The absorption spectra of three dyes on cellophane(treated and untreated) dyed using water, water­acetone, formamide-acetone and D MSO-acetone were

the same on both the films. Typical absorption spectraof three reactive dyes on treated cellophane arc shownin Figs 1-3. All the dyes gave two peaks. The band athigher wavelength, called as x, was attributed to themonomeric form of the dye, whereas the shorterwavelength band)' was attributed to the aggregated

form·1he extent of dye aggregation, expressed as yjxratio, was different when the dyeings were carried outusing different mediums. The aggregation ten'dencywas in the following order: water> water-acetone>

formanride-acetone ~ DMSO-acetone. Dye aggre­gation to a lesser extent on the film dyed from solvent­acetone medium was attributed to the disaggregationof the dyes in solution 30.

Rate offading curve-Fig. 4 shows that the fading atx band, is faster than at y band. A similar trend wasobserved for other dyes in all the mediums used fordyeing., Thus, the yjx ratio increased with the time offading. 'This increase can be attributed to the increase

in the average aggregation number. This was alsoI

,\ (nml

Fig. 1 - Absorption spectra of Red 31 on treated cellophane dyed indifferent mediums [(a) water, (b) water-acetone, (c) formamide­

acetone, and (d) OM SO-acetone]

CHAVAN & SUBRAMANIAN: L1GHTFASTNESS OF REACTIVE DYES ON CELLOPHANE

1.1 1.0

0-0--0 Trtahd cellophane fit••

~ Untrtattd cellophalll fin

>­>­VIZ~ 0.6

TIME, hr

Fig. 4-Change in J;X ratio with time of fading on cellophane filmdyed in aqueous medium (dye: Blue 5)

0.9o 200 400 600 000 1000

120 14060 80 1004020

--'...w>­Q.a

1.0

0-<>-0 Tr.ot.d cellophon. film

CH:H:I Untreated cellophon. film

TIME ,hr

Fig. 6-Fading rate curves of cellophane dyed with Orange 13 in

aqueous medium

>­>-VIZ•...o

160120 1~

0-0--0 Trtoted cellophane film

0--0---0 Untrtoted cellophane film

TI HE, hr

60 80 10040200.2

o

>-....V>Z0

06

~«w....Q.a

0.4

1.0

Fig. 5-Fading rate curves of cellophane dyed with Red 31 Inaqueous medium

TIHE,hr

Fig. 7 - Fading rate curves of cellophane dyed with Blue 5 in

aqueous medium

to dye penetration. The details of sodium zincatetreatment and the modification of the skin structure

are described in an earlier paper25 . The films dyedfrom aqueous medium showed higher lightfastness.This IT!aybe attributed to less dye aggregation both insolution and on substrate when dyeings were carriedout using a non-aqueous medium. Among the threedyes, Blue 5 showed very good lightfastness, whichmay be due to the anthraquinone structure of the dyeas suggested by the earlier workers I H.19.31 .

the monomeric dye form followed by slow fading ofthe aggregated dye, whereas c.I. Reactive Blue 5showed initially negative fading, i.e. the intensity ofthe colour actually increased with time (Fig. 7). This

trend appears to be due to the physical breakdown ofthe absorbed dye aggregates by the heat ofillumination3.

Characteristic fading curves-The characteristic

fading curves of reactive dyes on cellophane andtreated cellophane clearly indicated that the timerequired for I O~o fading on treated cellophane washigher than on normal cellophane at any particular

initial optical density, showing better fastness on theformer substrate (typical example is shown in Fig.8).

This may be attributed to the better penetration of dyein the former substrate, indicating the elimination ofhighly oriented skin structure which offers resistance

0.2o 200 400 600 800 1000

137

INDIAN 1. TEXT. RES., VOL. 9, DECEMBER 1984

3 Venkatraman K, Chemistry of synthetic dyes, Vol IV (Academic

Press Inc. London) 1971, 389.

4 Baronova G, Romanova M & Techekalin M. J Mendcleeug, 6

(1970) 700.5 Baronova G, Romanova M & Techekalin M, Tekst Prom. Mosk.

(1) (1972) 70.

6 Terenin A N, Photonics of dye molecules, (1977) 616.

7 Tschekalin M, Romanova M, Tekst Prom, Mask, 12 (1965) 51.

8 Krichevskii G E & Vachobov B, Text Res J, 45 (1975) 608.

9 Giles C H, Johari D P & Shah C D, Text Res J, 41 (1971) 83.

10 Giles C H, J Sac Dyers C%ur, 73 (1957) 127.

II Baxter G, Giles C H. Mckee M N & Macaulay N, J Sac Dyers

Colour, 71 (1955) 218.

12 Baxter G, Giies C H & Lewingston W J, J Sac Dyers Colour, 73(1957) 386.

13 Campbell D S E, Giles C H, J Soc Dyers C%ur, 74(1958) 164.14 Eaton J C, Giles C H & Gordon M. J Soc Dyers Colour, 68(1952)

394.

15 Giles C H, Baxter G, Black W. Macaulay N & Rahman S M K,Text Res J. 30 (1960) 934.

16 GilesC H.BaxterG& RahmanS M K, Text ResJ,31 (1961) 831.

17 Weissbein L & Coven G E, Text ResJ. 30 (1960) 58, 62.

18 Hildebrand D R. Chemtech. 8 (1978) 224.

19 Pisarvskanya V F. Androsov & Kuligina M S. Mastes Re.\p KantTeskst Khim. 3 (1974) 69.

20 Kissa E. Text Res J. 39 (1969) 734.

21 Kissa E. Texl Res J. 41 (1971) 715.

22 AATCC Delaware Valley Section, Text Chem Color, 5 (1973)60/49.

23 Silver H M, J Soe Dyers C%ur, 90 (1974) Ill.

24 Bose M. Sohelll dyeing of eOllon I\'ilh react ire dyes, M Techthesis. Indian Institute of Technology. New Delhi. 1976.

25 Chavan R B & Subramanian A. Indian J TeXI Res, 7 (1982) 10I.

26 Chavan R B. Text Res J. 46 (1976) 435.

27 Indian standard speeijiea/ions IS: 1889 (Indian StandardsInstitution. New Delhi) 1962.

28 Giles C H. Shah C D & Baillie D. J Soe Dyers Colour, 85 (1969)410.

29 Beech W F. Fihre reaelire dyes (Logos Press. London) 1970, 337.

30 Vickerslaff T. The physical chemistry oj'dyeing (Oliver & Boyd,London) 1954. Ch 2 and 3.

31 Gael S C. Pholoehelllislry (ij'reaelire dyes. M Tech thesis. IndianInstitute of Technology. New Delhi, 1980.

1000'-

800'" 700'0.E 600

-,,?

500

~ 400'-

.c::~ 300u.J~f=

2000.2

0.3 0.4 0.5 0.6 0.8 1.0

INITIAL OPTICAL DENSITY

Fig. 8 -Cfaracteristic fading curves of Blue 5 on treated anduntreated cellophane dyed in different mediums [( 0- 0 - 0)water; (li-+li-li)water-acetone; (0 -0 -0) formamide-acetone;

and ( x - x - x) DMSO-acetone]

References

I Egerton G S, Br Polym, 3 (1971) 63.

2 Giles q H & Mckay R B, Text Res J, 33 (1963) 528.

Conclusion

When the dyeing was carried out using water, water­acetone, formam ide-acetone and DMSO-acetonemediums, the three reactive dyes on cellophane were

J

present in the aggregated form as indicated by yjxratio. The extent of dye aggregation was in the order:water > water-acetone > formamide-acetone ~DMSO-acetone. Higher lightfastness obtained OIl"

sodium zincate-treated cellophane is attributed to thebetter d~e penetration due, in turn, to the eliminationof highly oriented skin structure.

138