Indi an Journal of Fibre & Textile Research Vol. 28, December 2003. pp. 43 1-436

Effect of dyes and finishes on UV protection of jute/cotton fabrics

S B Ghosh, P B ajaj & V K K otha ri "

Department of Textile Technol ogy. Indi an Institute of Technology, New Delhi 11001 6. India

Received 18 August 2002; revised received and accepted 10 December 2002

The effect of different dyes and fini shes on UV protection property of jute/cotton union fabrics has been stud ied. Bleach ing with H20 2 makes the fabr ics more permeabl e to UV rays. It is observed from spectral analysi s that the monochlorotriazinyl reactive dye with cyanuric ch loride nucleus. such as Cibacron Red FAL, is quite e ffec ti ve in UV protection. From the UV -vi sible spectral analysi s, Cibatex UPF is found to be a suitable fini shing agent for rendering sufficient UV protection to the jute/cotton fabric. Simultaneous dyeing and fini shing wi th Cibacron Red FAL and Cibatex UPF provides higher UV protection . The treatment of jute/colton fab ri c with titanium dioxide also provides satisfac to ry protection against UV rays.

Keywords: Dyes. Jute/colton union fabrics , UV absorbers, UV protection

1 Introduction The risks posed by ultraviolet radiation have

become noteworthy in recent years as the concerns over environmenta l issues, particularly the thinning of the earth ' s protective layer, increase. The occurrence of skin cancer due to over exposure to harmful ultraviolet rays of solar radiation has been on the rise. Thus, it is important to protect the skin from excessive exposure to UV radiation . On the basi s of wavelength, the ultraviolet (UV) radiation fall s into three categories: UV -C 0..<280 nm), UV -B ("-=280-320 nm) and UV -A ("-=320-400 nm). In order to provide a good level of protection, the textile worn as clothing should shield human skin against these harmful radiations. Studies'·5 have revealed that the UV protection offered by a fabric is dependent on a number of factors, including fibre type, fabric construction , nature of chemical processing undergone by the fabric and the presence of additi ves such as UV absorbers and optical brighteners. It can be found from the literature5

.6 that natural cellulosic

fibres have a low to moderate UV absorption capac ity. Wool and silk, although have higher absorption than cellulosics, provide less UV protection than the synthetic fibres. Polyester and aromatic polyamjdes have higher absorption in the UV region due to the presence of aromaticity in comparison to aliphatic polyamides6

.

"To whom all the correspondence should be addressed. Phone: 26591407 ; Fax: 0091 -011-26862037; Email: kothari @textile .i itd.ernet.in

Construction of the fabric and moisturelre lative humidity also affect the ultraviolet protec ti on property of the fabric. Dyes, especially those havi ng chemical structure that resembles (or modif ies by e lectronic rearrangement on exposure to solar spectrum) to those of the UV absorbers , improve the sun protection property of the fabric s ignificantl / ·" . UV absorbers '2. '7 spec iall y based on tri az ine. benzotriazole and benzophenone can a lso reduce the tota l amount of radiation affec ting the sk in.

So far, no detailed study has been reported on UV permeation of jute fabric s. In thi s paper, the potentia l of jute/cotton union fabric on UV protection has been reported. Jute was chosen as one of the component fibres because of the aromaticity in its li gnin structure' 8.20, biodegradability and moist ure absorption capacity. The use of suitab le sun protec ti ve dyes and finishes for application on such jute/cotton union fabric has also been studied. For eva luat ion of UV protection, an indirec t economic approach based on photo fading of a standard dyed wool fabri c is described.

2 Materials and Methods 2.1 Materials

100% jute and three jute/cotton uni on woven fabrics in grey state were used. The spec ifications of the fabrics are given in Table 1.

Monochlorotri azi nyl reacti ve dye Ci bacron Red FAL, Solophenyl Turquoi se Blue BRLE dye, and auxili ary chemica ls such as penetrati on accelerant

432 INDIAN J. F!BRE TEXT. RES ., DECEMBER 2003

Table I - Specifications of fabrics

Fabric Ends/m Picks/m Warp count lex

Weft count lex

Weight g/m2

100 % Jute fabric

Jute/cotton union fabric (warp - cotton; weft - jute)

800

1800

(Cibatluid C) and dye bath conditioner (Cibacel DBC) were used on the selected fabrics. Two UV absorbers, namely Cibatex UPF from Ciba Speciality Chemicals and Rayosan C from Clariant (India) Limited, were also used along with titanium dioxide (Ti02) sieved through 80 mesh filter.

2.2 Methods 2.2.1 Bleaching with 1-1 20 2

The bleaching of jute/cotton union fabrics was carr ied with 30 gIL H20 2 at a material -to-liquor ratio of I :30. Sodium sil icate and sodium carbonate were added to the bleaching bath. The temperature was 850C and pH was maintained between 10.5 and 11.

2.2.2 Dyeing with Cibacron Red FAL

Dyeing was carried by the exhaust method in a Julabo shaking water bath at 600C for 110 min , maintaining the material-to-liquor ratio at 1 :50. A buffer with sodi um acetate and acetic acid was used in the dye bath to get a constant pH of 8.5. The dyed fabric was cold rinsed, neutralized with acetic acid and fina ll y hot rinsed.

2.2.3 Dyeing with Solophenyl Turquoise Blue BRLE

The dye bath was prepared with the Solophenyl Turquoise Blue BRLE and auxiliaries at a material-to­liquor ratio of I :30. The dye solution was buffered with sodium acetate and acetic acid to give a constant pH of 8.5. Dyeing was carried out over a period of 110 min in J ul abo shaking water bath. The dyeing cycle is shown in Fig 1.

2.2,4 Simultaneous Dyeing and Finishing with UV Absorber

Cibatex UPF/Rayosan C was dissolved in hot water and applied by exhaustion (2%) from the dye bath along with Cibacron Red FAL and Solophenyl Turquoise Blue BRLE dyes at a material-to-liquor ratio of 1: 15. The application conditions were same as those for the respective dyes.

Titanium dioxide (Ti02) was app lied on both grey and bleached jute/cotton union fabrics by dispersing fine Ti02 in ethylene g lycol with IglL non-ionic detergent (Lissapol N) followed by padding at 80% ex pression.

750 '

1000

241

33.2

241

172

374

232

1oor-----------~==========~--------~

80

40

20~0----2~0----~4 0----'60----~8'O ----I O'0----,2rO--~,4 0

Dyeing time/min

Fi g. I - Dyeing cycle of Solophcnyl Blue BRLE

2.2.5 Recording of UV -Visible Spectra

The UV -visible spectra of dyes and UV absorbers were recorded on Pharmacia LKB Biochrom 4060 UV -v isible spectrophotometer.

2.2.6 Measurement of Colour Strength

Jute/cotton fabrics (232g/m2) were dyed (2% owf) and finished (2% owf) in a s ingle bath using the method described in sec tion 2.2.4 and the dyed wool samples were protected with these fabrics . The reflectance of dyed samples was measured on JAYPAK Computer Colour Matching System 4801 using 100 observer and D65 illuminant. The K/S va lues were measured at 630 nm A.ma x.

2.2.7 Evaluation of UV Protection A specia lly designed spect rophotomete r with an

integrating sphere is normally used for the measurement of UV protection offered by a fabric . However, in the present study, an indirect method 21 of evaluating UV protection was adopted . Wool fabric of 300 g/m2 was dyed with an acid dye (el Acid Blue 6) of poor light fastness (1 -2, measured by lSO-lI) so that it can be eas il y faded by the UV radiati on. Thi s dyed wool fabric was covered with di fferent fabri c samples, namely bleached, dyed, and dyed and finished combined together (Fig. 2). The assembli es were exposed for a total duration of 96 h.

GHOSH el al.: UV PROTECTION OF JUTflCOTTON FABRICS 433

2

3

Fig. 2 - Set-up for the alternative method of measurement of ultraviolet protection factor [1 - MBTF bulb (UV source), 2 -sample, and 3 - dyed wool fabric]

To investigate the rate of fading, the K/S values of the respective dyed wool fabrics were recorded at the maximum wavelengths after periodic exposure of 48 h, 72 hand 96 h in MBTF (Mercury Bulb Tungsten Filament) having a A max of 340 nm.

3 Results and Discussion 3.1 Influence of Jute Lignin on UV Protection

J ute/cotton union and 100% jute woven grey fabrics of nearly same cover factor and weight were used . Jute fabric protected wool sample shows higher K/S value, even after 96 h of exposure, than that of the jute/cotton union fabric (Fig 3). The results indicate that the pure jute fabric provides a higher protection against UV rays than a jute/cotton fabric . The presence of lignin in jute makes it less permeable to UV rays as it acts as an UV absorber. Jute lignin absorbs strongly in far UV region (230-240 nm and 270-290 nm) as has already been reported in literature 19.20.

3.2 Spectral Analysis of Dyes

Selection of sun protective dyes was done on the basis of their UV - visible spectra. The UV -visible spectrum of Cibacron Red FAL dye (Fig 4) shows strong absorption' in UV -C region (230-240 nm and 270- 290 nm) and moderate absorpt ion band in UV­B region . In the visib le reg ion, the dye absorbs at 517 and 545 nm. UV - visib le spectrum of Solo­phenyl Turquoise Blue BRLE (Fig. 5) shows weak absorption in the UV -C region (250-270 nm), while in the UV-A region it shows moderate absorption peak at 332nm. However, in the visib le region the

" " " > Vl

>2

~ 1

30 1- IOO%jute fabric (grey) 2---Grey jute/cotton (50:50) union fabric

29

28

27

26

25

24 a 20 40 60 BO 12 0 100

Time of Exposure (h)

Fig. 3 - Effect of jute proportion on UV protection

231. 1.0

517 51.5

o 2~00~----~30~0-------40LO-------SOLO----~6uOO

Wavelength (nm)

Fig. 4 - UV-visible spectrum ofCibacron Red FAL

dye absorbs strongly (Fig.5). A comparison of ab­sorption spectra of these dyes indicates that the Ci­bacron Red FAL should be more effective in UV protection than Solophenyl Turquoi se B lue BRLE because of its strong absorption in UV region.

3.3 Spectral Analysis of UV Absorber To establish the effectiveness of UV absorbers in

cutting of UV rays, the UV absorption spectra of two UV absorbers (Cibatex UPF and Rayosan C) were taken . A comparative study of these absorpti on spectra (Fig. 6) reveal s that the Cibatex UPF absorbs strongly at 290 nm A 111" X in UV -B region. The spectrum also encompasses a wider region , indi catin g that it should be quite effec tive in cutting of UV rays. Absorption spectra of Rayosan C paste show an absorption maxima at 277 nm Am,x; in the UV-A region , however, the absorpti on is ve ry low.

434 IND IAN 1. FIBRE TEXT RES. , DECEMBER 2003

Table 2 - Effect of jute proport ion , chemical treatments and UV radiation on UV protection of jute and jute/cotton union fahri cs

KIS of dyed wool before exposure to UV radiati on

30.06

Time of exposure

h

48 72 96

Grey jute/cotton union fabric

26.79 26.33 25. 19

a·6 ....----------- - ----------,

Q) u c

"' .0 o "' .0

0 4

« a.2

606

~·~aa~-~~-~~-~~L--~6aLa---7~O-O~~-Boa Wavelength (nm)

Fi g. 5 - UV -visible spectrum of Solophenyl Blue BRLE

A hi gher UV protecti on is thus expected wi th Cibatex UPF. Further, the extinct ion coefficient of Cibatex UPF at the maximum wavelength being higher than that of Rayosan C paste, it is expected to be more effective at much lower concentrations.

3.4 Effect of Bleaching A compari son between the K/S values of the dyed

wool samples protected by both grey and bleached jutelcotton fabrics reveals (Table 2) that with bleached fabric , the KlS value of the wool sample reduces to the least (from 30.06 to 24.92). This indicates that the bleached jutelcotton fabri c is highly permeable to the UV rays and hence should offer least U\! protection. On the other hand, the grey j ute/cotton fabric offers higher protection to UV rays as in thi s case the K/S value decreases from 30.06 to 25.19. The above resu lts indicate that because of the natural UV absorbers (lignin and pectin) in the fabric , during bleaching there is an increase in permeability to UV rays.

3.5 Effect of Sun Protective Dyes

To explore the effectiveness of Cibacron Red FAL and Solophenyl Turquoise Blue BRLE, the overall fad ing of dyed wool samples was measured on exposure to UV radiation after covering with dyed jute cotton fabrics. The measurement of K/S values of the wool samples covered by Cibacron Red FAL and Solophenyl Turquoise Blue BRLE dyed fabrics shows

KJS of dyed wool after exposure to UV radiati on Bleached jute/cotton Ti02 treated jute/cotton

union fabric un ion fabri c 100',;i jute

fahri c

26 04 25 .89 24.92

28. 7 1 27.42 27.4 1

27.91 21.42 274 2

2 . 5r---------------~

I 289 - Ciba t ex UP F I 2.a II - - - - Ruyoson C

II I I

I I

" a.5

I I

I

/ I

/

277 --, , \ ,

\ \ \ \

\ \

Wavelength (nm)

Fig. 6 - Comparative study of the UV spectra of Cibalex UPF and Rayosan C paste

31 .---------------------------~

30 -

28 -

l-Cibacron (4 % ow!) 2- So lophenyl (4 % owl)

3- Ci bacron (2 % owl) 4---Solophenyl (2 % ow!)

2

3 4 27+-_________________ : ________ ~

o 50 100 150

Time of Exposure (h) Fig. 7 - Effect of dyes on UV protecti on

that the Cibacron Red FAL cut the UV rays more effectively than the Solophenyl Turquoise Blue BRLE (Fig.7). This is because while Solophenyl Blue BRLE contains a pthalocyanin chromophore (S tructure J). the Cibacron Red FAL contains a cyanuric chl oride nucleus

attached to at least one dye chromophore (Structure D). Thi s causes the e lectronic tran siti on (due to the interaction with the elec tromagnetic UV radiati on) in the C ibacron Red FAL to take pl ace at a much lower energy level and hence makes it a better absorber of UV radiation. It can also be observed that the higher concentration (4% owf) of the dyes can provide higher UV protection as compared to lower concentration (2% owf) of the dyes. The above observations are we ll

GHOSH et af.: UV PROTECTION OF JUTE/COTTON FABR ICS 435

'" " <ij > VJ

~

4 " C.f N'c1'~ "" I II / c- N N- C ~ "- II" ,'"

N Cu " N '" /"- / C=N N- C

/ I I ~ ~/C""N/C ~o SO,N.

Structure I

/ Dye-NH - C

I ~N=C

Structure II

'-CI

30 ~------------------------------~

29.5

29

28.5

28

27.5

27 ~----------~----~------~----~ o 20 40 60 80 100

Time of Exposure (h) Fig. 8- Effect of dyes and finishes on UV protection [1 - Cibacron (2% owf) + Cibatex UPF (2% owf), 2 - Cibacron (2% owf) + Rayosan C(2% ow!), 3 - Solophenyl (2% ow!) + Rayosan C (2% ow!) and 4 - Solophenyl (2% owf) + Cibatex UPF (2% owf)]

supported by the spectral analysis of these dyes in the UV -visible region as discussed earlier.

3.6 Performance of Simultaneously Dyed and Finished Fabrics in UV Protection A comparison of the K/S values of the samples

after 96 h of exposure to UV radiation shows that the combi nation of Cibacron Red FAL and Cibatex UPF provides least permeation and hence hi ghest protection to UV rays (Fig. 8). On the other hand , on comparing the protec tive performance of the

Solophenyl Turquoise Blue BRLE and the finishes. a somewhat different trend was observed. Rayosan C paste shows higher protection with the above dye than Cibatex UPF when the exposure time is low. It is interesting to note that in a ll the cases the action of UV absorbers is addit ive rather than synerg istic . Apparently, this may be justified by the fact that these dyes have absorpt ion maxima in the UV region which can protect the wool fabrics from photo fading due [ 0

UV radiation exposure and the presence of UV absorbers, although enhances the UV protec ti on , the effect is not so significant.

3.7 Influence of TiOz The presence of Ti02 particles in a fabric results in

scattering of UV rays and thus makes it less permeable to UV rays . In order to in vest igate the effectiveness of Ti02, the K/S measure ments were carried out with Ti02-treated jute/cotton uni on fabric (232 g/m"). The results indicate that even after 96 h of exposures the fabr ic provides higher protect ion than both grey and bleac hed jute/cotton union fabric s (Table 2). This indicates that Ti02 is quite effecti ve in UV protection .

4 Conclusions 100% grey jute fabric provides higher protect ion than

both grey and bleached jute/cotton union fabric s. Monochlorotriazinyl reactive dye with cyanuric ch loride nuc leus, such as Cibacron Reactive Red FAL, imparts suffic ient protection to jute/cotton fabric against harmful UV rays. Simultaneous dyeing and fini shing with Cibacron Reactive Red FAL and Cibatex UPF makes a jute/cotton fabric highly protective against UV rays. T itanium dioxide can be effectively used as a fini shing agent for sun protective clothing.

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