Indian Journal o r Fibre & Tex tile Research Vol. 27, December 2002, pp. 4 17 -42 1

Effect of pretreatments on ambient temperature bleaching and reactive dyeing of jute

S N C hatlOpadhyay, N C Pa n &. A Day"

C hemical & Bioche mi cal Process ing Divi s ion , National In stitute or Resea rch on Jute & Alli ed Fibre Tec hno logy, 12 Regent Park. Ko lkata 700040. India

N£'ceil'ed 6 A/lgust 2001; rel'is£'d receil'ed a/lli accepted 22 Novell/her 200 1

Bl eaching or g rey j ute ya rn by conventional ho t hydrogen pe roxide bleaching, ambient te mperature bleaching and ambient temperature bleaching us ing spent liquo r has been studi ed. Be ro re bleaching, the jute ya rns were e ither scoured or treated with a lkali at ambient tc mpe ralUre. One set o r a lka li- trea ted jute yarns was washed, dri ed and then used ror bleac hing and the other set or a lka li -trea ted ya rns was dried without washing and used ro r bleaching. A I: the b leac hed sa mpl es were dycd at room temperallire using co ld brand reac ti ve dye. It is found that the whiteness and bri ghtness indi ces or the j ute yarn sam ples bleached by conventi ona l process ro llow the o lder: grey bleached >scoured and bleached > a lka li -trea ted (w it hout wash) and bleached> a lka li -treatcd (w ith wash) and bl eac hed. For ambi ent tempera ture h leached samples . the o rde r is : grey b leached > scoured and bleac hed> a lkali -trea ted (w ith wash) and bleached > a lka li -trcated (wi thout wash) and bleached . The dye uptake va lue inc reases with the ro ll ow ing o rde r or pretrea tments: alka li-treated (w ith out wash) > alka li-tn:ated (w ith wash» scou red > grey.

Keywords : Bleaching. Bri gh tness index , Dyei ng. Dye uptake. Scouring, Wash rastness , W hiteness index

1 Introduction The eco-friendl y and biodegradab le nature of' j ute

fibre along wi th its tenac ity and long staple length has made th is fi bre attract ive in thc fi e ld o f' textiles and other decorat ive cnd uses worldwide. The natural golden fibrc needs proper chcmica l process ing, viz. prctreatment , bleaching, dycing and aftertreatment , to makc it att ractive to thc customer. Process ing of jute is diffi cult due to its complex chemica l structure i.e. ce ll ulosc, hemi ce liulose and li gnin CO I:1pos iti on. A parti cul ar chemi cal treatmcnt may be benefici al to one component bu t detri menta l to other. Therefore, a balance is to be mai ntained during its chemica l processing to get the optimum cffect. Bleaching of jute is done in such a way that it produces creamy white fibre ra ther than milk y white fibre to avoid the damage of the fibre. Si mil arl y, thc dycing process is also selected in such a way that it does not damage the fibrc and at the samc timc results in optimum fastness and dye uptake. Moreovcr, thc jute product ,being heavy in nature, requircs a lot of water to maintain a desirab le material-to- li quor ratio as we ll as the dry ing of the material requires lot of encrgy.

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To sol ve the above problems, the present work was aimed at chemi ca l processing of jute ya rn at ambi ent temperature. The proccss !-:1 requires less water, less energy and the damage to the fibre is minimu m while using the conventional tex ti le machineri es withou t additi onal capi ra l in vcstment. The process is also sui tabl e for small and cottage indust ry. Water and environment pollution problem is less in thi s process whi ch makes reuse of chemical solution . As the whole process is carri ed out at ambient conditi on, it is easy to control the processing conditi on and thc hea lth hazard problem to the labour is also mini mi zed. Conventi onal processing has also been carried out to compare the new process with the conventional process. An attcmpt has also been made to make the process economi c, eco-fri endl y and energy effici en t.

2 Materials and Methods 2.1 Materials 2.1.1 Substrate

The spinning of grey j ute fibre was done in a j utc spinning system. The average count of jutc ya rn produced was 235 tex .

2.1 .2 C hemicals

Hydrogen perox idc, sodi um hydrox ide. sodium si li ca te, tri sod iu m phosphate, magnes ium sulphate

4 18 INDIAN J. FIBRE TEXT. RES. , DECEMBER 2002

heptahydrate, sodi um persu lphate, sod ium sulph ate, Ultravon JU (non-ionic detergent) and acet ic acid, all of analyt ical grade, were used.

2.1.3 Dye

Cold brand reactive dye Procion Red M8B (supplied by Mis Hindusthan Ciba-Geigy Limited, Mumbai) was used for dyeing of jute yarn .

2.2 Methods

A diagrammatic flow chart of the total experiment is shown in Fig. I.

2.2.1 Scouring Grey jute yarn was scou red with sod ium hyd rox ide

(2 giL) and non-ionic detergent (5 giL) at 100°C for I h, keeping the material-to-liquor ratio at 1 :20. After scouring, the yarn was washed thoroughly in hot water and co ld water in success ion and neutrali zed with aceti c ac id (2 milL) followed by usual washing.

2.2.2 Alkali Treatment

Grey jute yarn was treated with sod ium hydroxide( I Og/L) and non-ionic detergent (2 giL) at ambient temperature (30" C) for 4 h, keeping the material-to-I iquor rati o at I: 10. A fter the treatment, one set of yarn sample was taken out from the solution, sq ueezed and dried in air. The other set of yarn sample was washed thoroughl y in cold water,

neutrali zed with acetic acid (2 milL), agall1 washed and finally dried in air.

2.2.3 Conventional Bleaching

Bleaching of grey, scoured and alkali-treated jute ya rn samples was done in a closed vessel for 2 h at 90" C, keeping the material-to-liquor ratio at 1 :20, with hydrogen peroxide ( I vo l. ), trisodium phosphate (5 giL), sodium hydroxide (I gIL), sodiu m silicate (10 giL) and non-ionic detergent (2 giL). After bleaching, the yarn samples were washed thoroughly in cold water, neutrali zed with acetic acid (2 milL), again washed and finally dried in air.

2.2.4 Amhient Temperature Bleaching

Grey , scoured and alkal i- t'cated jute ya rn samples intended for ambient temperature bleaching were separately dipped in the solution containing hydrogen peroxide ( to vol. ), sodium sili cate (20 giL), sod ium hyd rox ide (20 giL ), tri sod ium phosphate (5 giL), sodium persulphate (10 giL), magnesium sulph ate heptahydrate (0.5 giL), Ultravon JU ( 10 giL) and sq ueezed to give 80% wet pick-up. The samples were then put in a plastic bag and kept overn ight , washed in cold water, neutra lized in aceti c ac id (2 milL) , aga in washed and dried at room temperature.

2.2.5 Ambient Temperature Bleaching using Spent Liquor

The liquor left out after ambient temperature

Fig. I - Diagrammatic flow chart of the towl experiment represented by the alphabets to indicate process alternatives

C HATTOPADHYAY el al. : EFFECT OF PR ETR EATM ENTS O N BLEACHI NG & DY EING OF JUT E 4 19

bleaching as in 2.2.4 was reused for the preparation of second batch of sample so th at the effluent di sposal problem is minimum. Grey, scoured and alkali -treated jute yarn samples intended for ambient temperature bleaching (using spent liquor ) were dipped in the spent liquor and squeezed to g ive 80% wet pi ck-up. The samples were then put in a pl asti c bag and kept overnight, washed in cold water, neutralized in acetic acid (2mIlL) , again washed with cold water and dried at room temperature.

2.2.6 Dyeing Grey conventi o nal bleached, scoured and

conventional bleached , alkali- treated and conventional bleached, grey ambient temperature bleached, scoured and ambient temperature bleached , alkali -treated and ambient temperature bleached jute yarn samples were dyed with co ld brand reacti ve dye Procion Red M8B under the foll owing conditio ns:

Dye bath was prepared with dye (4% owm) and Glauber's sa lt (60 giL), keeping the material-to-liquor ratio at 1 :20. The yarn sampl es were dipped into the dye bath and kept fo r I h with stirring at a temperature o f 30° C. After thi s, sodium carbonate (20 giL) was added in the same bath and kept for 45 min in the same condition. Thereafter, the samples were washed with cold water, soaped with Ultravon JU (2 giL) fo r 15 min foll owed by usual washing and drying in air.

2.2.7 Determination of the Physico-chemical Properties 2.2.7.1 Whiteness Index, Yellowness Index and Brightness

Index Whiteness index in the ' HUNTE R' scale,

yellowness index in the 'ASTM 0 1925' scale and brightness index in the 'T APPI 45' scale of the grey , scoured, a lkali- treated, grey b leached ,scoured and bleached, alkali-treated and bleached jute ya rn samples were measured by the Spectrascan-5100® computer colour matching system using re levant softwares.

2.2.7.2 Amax and KIS Values Spectrascan-5100® computer colo ur matching

system was used to measure Amax and KIS values.

2.2.7.3 Wash Fastness All the reacti ve dyed ju te yarn samples were

subjected to wash fastness test in a launder-O-meter as per IS : 336 1-1979 (ref A). Wash fastness ratings o f a ll the dyed jute yarn samples were evaluated with the help of computer colour matching system.

3 Results and Discussion It is clear from Table 1 that the co nventional

bleaching produces better white yarn as compared to ambient temperature b leaching whether it is done by using ori ginal liquor or spent liquor. It may be due to the removal of impuriti es at a lkaline bo iling whi ch gives oppo rtunity to the bleaching agent to react immedi ate ly on the fibre. Ambient temperature bleaching fro m orig inal bath produces better whiteness compared to that from spent liquor due LO

the obvious reason. The difference in whiteness and bri ghtness indi ces o f the yarn produced by grey­bleach or scour-bleach process is minimum in case of ambient temperature bleaching co mpared to the conventi onal bleaching (T able I).

Alka li treatment at ambi ent conditio n swell s the yarn and takes out impurities and non-ce ll ulosic matters like hemi cellul ose, li gnin , etc. o n the sur face. Therefore, the yarn becomes darker after al kali treatment, but if the yarn is washed , it beco mes bri ghter co mpared to grey yarn whi ch is evident fro m Tabl e 2. Alkali -treated yarn with wash behaves like

Table I- Effect of scouring o n conventi onal and ambient te mpera ture bleaching

Sampl e White ness Yell owness Brightness index index index

(HUNTER) (ASTM D 1925) (T APPI 45)

A 45.28 47 .72 16.57

B 46.53 47.07 17.86

C 77.92 24.95 55 .19

D 73.9 1 30.49 47.78

E 7 I.7 1 22 .84 47.35

F 70.2 1 34 .17 42.3 1

G 67.79 28 .42 40 .88

H 66.64 39.9 1 36.76

Table 2 - EITeCl o f bleaching o n alka li -trea ted jute ya rns with wash or withou t wash

Sample White ness index Ye ll ow ness index Brightness index (HUNT ER) (AST M D 1925) (T APPI 45 )

48 .06 47.48 18.92

4 1.3 1 60.8 1 12 .57

K 74. 11 24.77 49.6 1

L 69.78 32.47 42.23

M 74.96 20.28 5 1.86

N 66.77 38.5 1 37.8 1

0 68.53 39.5 1 39.87

P 67 .37 39.65 37.78

Q 64.42 39.42 34 .8 1

R 66.26 38.86 36.83

420 INDI AN J. FIBRE TEXT. RES. , DECEMB ER 2002

scoured ya rn and after hot conventional bleaching it gives whiteness as that of scoured and bleached yarn . If the alkali-treated ya rns are dried without wash, they produce high alkal ine condition during bl eaching. Therefore, in hot conventi onal bleaching, the whi teness and brightness indices drop significantly . Experiments have show n th at the alkali -treated without wash ya rn s release about 1.6 giL sod ium hydrox ide in I : 20 material -to- liquor ratio condition. if these ya rns are subjected to hot bl each without adding any alkali during bleaching, they produce wh iteness as that of scoured and bleached yarns. Alka li-treated ya rns dried without wash have impuri ties present on the surface of the swe ll ed yarn structu re ancl when subjected to ambient temperature bleaching they produce better whiteness compared to that of alkali-treated (w ith wash) ambient temperature bleached yarn . Thi s may be due to high alka linity, swelled structure and the impurities being present on the surface easi ly attacked by bieaching agent. Thi s finding is true for both original liquor ambient temperature bleaching and spent liquor ambi ent temperature bl eaching.

Table 3 shows the dyeing behaviour of scoured and bleached jute yarn s. The scoured and hot conven tional bleached j ute yarn shows marginal hi gher dye uptake compared to contro l yarn . This may be due to the thorough remova l of impuriti es present on the surface of jute yarn during scouring. Ambient temperature bleaching was done at higher alkaline condition which resul ts in swell ing of the yarn to some extent. Therefore, the ambient temperature bleached jute yarn shows better dye uptake compared to the contro l jute yarn. Scoured and ambient temperature bleached jute ya rn shows even better dye uptake. Table 3 shows that the ya rns subjected to ambient temperature bleaching using spent liquor have a tendency of better dye uptake compared to the only ambient temperatu re bleached yarn if the yarn is bleached after scouring. Wash fastness property of dyed yarns is equa lly good for all the samples.

Two - step swelling of jute yarn, one during alkali treatment and another duri ng ambient temperature bleach ing, exposed more nlllnber of reactive hydroxyl groups to reactive dye and as a result the higher dye uptake is seen in case of alka li-treated ambient temperature bleached jute yarn (Table 4). If alka li ­treated sampl es are not washed before ambient temperature bleaching, they yield even better dye uptake. This finding is true for both ori ginal liquor ambient temperature bleaching and spent liquor

Table 3 - Effect of diffcrent bleaching proccsses on dyei ng with cold brand reac ti ve dye

Sample KIS Colour Reflectancc Wash va lue strcngth. % fastness

C 10.71 100.00 4.2k 4

D 11 .12 /03.9 1 4'(n 4

E 11.61 108.39 3.% 4

r' -. 11 .73 109.65 3.93 3

G 11.73 109.67 3')3 2-3

H /2.0 1 11 2.2l) ].~~ 4

Tablc 4 - Effect of diffcrent a lkali pretrC;Jt lTlCllt s and suhsequent blcaching on dyeing behaviou r' with

cold hrand rcactive dye

Samplc K IS Co lour Rcfl ect ance Wash va llie strength , % fa stness

C 10.7 1 100.00 4.28 4

K 10.79 100.91 4.25 3-4

L 11.3 1 105.76 4.07 3

M 11 .25 105.22 4.09 4

N /2. 19 /1 3.98 :I.R I 3-4

0 12.R3 11 9.93 3.62 4

P 11.44 106.93 4.0:1 3-4

Q 11 .44 106.9:1 4.03 4

R 11.99 11 2.04 3.l) (i 4

ambient temperature bleaching. Experimen ts have shown that about 9 giL sodium hydrox ide is re leased in 1: 3 materi al-to-liquor rati o condi tion if alka li ­treated samples are not washed. If ambi ent temperature bleaching is carri ed out wi thout further addit ion of alka li during bleaching, no extra swelling takes pl ace during bleaching, resulting in lower dye uptake, Therefore , alka li treatment without wash fo ll owed by ambient temperature bl eaching and then dyeing with Procion Red M88 res ults in hi ghel dye uptake.

4 Conclusions 4.1 Ambient temperature bleaching and reacti ve dyeing is simple, economical, energy sav ing, eco­fri end ly and can be clone by using conventional textile machinery. The process is suitable fo r sma ll-scale and cottage industries. 4.2 Ambient temperature suffi cient whiteness suitable dyeing.

bleaching produces for subseq uent use in

4.3 Ambient temperat ure bleaching using spent liquor is economical, minimi zes the efnuent and produces sufficient whiteness for subsequent use in dye ing.

CHATTOPADHYAY ('I a/.: EFFECT OF PRETREATMENTS ON BLEACHING & DYEING OF JUTE 42 1

4.4 Ambient temperature bleaching of alkali-treated yarn without wash produces superior whiteness as compared to that of the ambient temperature bleached yarn pre-treated with alkali (w ith wash). If alkali­treated ya rn without wash is used for conventi onal hot bleaching, addition of further alkali is not required during bleaching and the whiteness obtained is same as that of scoured and hot bleached yarn . .t.5 Ambient temperature bleached yarn always shows higher reacti ve dye uptake compared to that of conventional bleached yarn. Scoured and ambient temperature bleached yarn is even better in this respect. .t.6 Alkali-treated yarn without wash on ambient temperature bleaching and then dyeing with co ld brand react ive dye produces maximum dye uptake.

Therefore , for the production of same dep th of shade, this yarn requires around 20% less dye than th at required by the grey conventional bleached yarn. 4.7 For ambient temperature process ing. alkali treatment without "vash followed by aillo icnt temperature bleachi ng produces better wh i tc nc:-.. .1Ile.! the dye uptake is also max imum.

References I P~nclcy S N, Chattopadhyay S N & Basu G, Illdiall .I Fi/m'

Texl Res. 20 ( 1995) 102.

2 B~su G & Chall opad hyay S N. I lldiall .I Fibre Texl N('\'. 21( 1996) 217.

:I Ch;l ttopadhyay S N, Pan N C & Day A, Tnl Trel/{/s. XLII I (200 1) 2]

-+ IS 3]61-1979 .1SI I-Iolld/mot.: oj' Texli /e Tesl i llg (8ureau oj' Indi an Standards. CIY Delhi). IlIS2.