Indian Journal of Textile ResearchVol. 12, March 1987, Pp. 36-39

Spinnability of Jute Fibres with Special Reference to Bleached Jute

U DAllA, T K GUHA ROY, S CHATIERJEE, U K GHOSH and B SIKDAR

Indian Jute Industries' Research Association, Calcutta 700 088, India

Received 16 April 1986; accepted 10 June 1986

The changes in jute fibre properties at various degrees of bleaching are reported. The changes in processingparameters, found necessary during semi-bulk and bulk trials in the mills, along with the limitation in spinnabilityof jute, are discussed. Up to 3% concentration of H202 there was no problem in spinning, only higher twist wasnecessary. Above this, the bundle tenacity of fibre decreased rapidly and hence adjustments in carding and spinn-ing were essential. For efficient spinning the limiting value of bundle tenacity was 13 g!tex.

Keywords: Bleaching, Jute fibre, Spinning

1 IntroductionBleaching of jute is one of the important means of

diversifying jute goods so as to promote its uses in de-corative and furnishing materials such as wall covers,curtains and upholsteries. The conventional bleach-ing process involves bleaching at fabric stage withwet-processing machinery. The drawbacks are highprocessing cost, high capital investment in the settingup of a plant and loss in weight and shrinkage of fabricwidth. As a result, it prevents many mills from enter-ing into this field.

With a view to overcoming these drawbacks to alarge extent, UIRA developed a simple and economicprocess of bleaching jute fibres at the fibre prepara-tion stage (batching)'. Any mill can adopt the processas it dispenses with wet-processing machinery. Thebleached fibres are processed through the normal se-quence of carding, drawing, spinning and weavingthrough the conventional machinery.

The process consists in incorporating a bleachingagent and auxiliary chemicals with a jute batching oil(JBO) emulsion and its application of fibres in suchconcentrations as to achieve the desired degree ofwhiteness.

In this process, the fibre properties change owing tothe application of the bleaching agent. The degree ofchange depends on the concentration of the bleachingagent. Because of the change in fibre properties, thespionability of the fibres also changes. Hence pro-cessing parameters of carding and spinning requiresome changes in order to achieve satisfactory spion-ing efficiency and yarn quality.

In this paper, the changes in fibre properties at var-ious degrees of bleaching are reported. The changesin processing parameters found necessary during se-mi-bulk and bulk trials in mills are discussed alongwith some experiments to achieve the optimum va-

36

lues of the parameters. An attempt has also beenmade to find out the limitations in spionability of jutewith respect to spinning performance and yarn tenac-ity against fibre tenacity, which is the most importantcriterion of the fibre properties. Further, the twist fac-tor for processing weak fibres has been optimized toachieve optimum yarn tenacity.

2 Materials and MethodsStandard grades of TO 32 and W32 jute were used in

the proportion 7:3, and hydrogen peroxide was usedas a bleaching agent. The dry-cut jute was pro-cessed through a dry softener machine to free the fi-bres from foreign matters like dirt, dust and specks,and to soften the fibres machanically so that the chem-icals can easily penetrate into the fibres. The chemi-cals were sprayed over the fibres along with the jutebatching oil (JBO) emulsion in proportion to theweight of jute. The application was restricted to be-tween 20 and 30% depending upon RH of the atmos-phere. The application of JBO was maintained at 2%,the application ofH202 being varied up to 6%. The fi-bres were later piled for 48-72 h depending on theconcentration of H202 applied.

The bundle tenacity (g/tex) of raw jute was deter-mined before and after the treatment for each qualityof jute on a Scott fabric strength tester at a gaugelength of 5 em with a constant rate of traverse (30 em/min). The average of 30 measurements was calculat-ed. Fineness was determined by the air flow method-and the average fibre length in the breaker card sliverwas determined according to the method developedby Mukhopadhyay and Bhattacharyya".

During carding, droppings beneath the cards wereweighed and expressed as percentage of the totalweight of jute processed for different types of cardsavailable in the industry. The carding intensity' was

DATfA etal.: SPINNABIUTY Of JUTE FIBRES

Table I-Fibre Fineness (denier) at Various Degrees of Bleaching 1D3 and W3 Grades of JuteGrade of jute Fibre fineness at different cone. of H202

0% 1% 3%22 ± 1.0TD 3 22 ± 1.1 25 ± 1.1 22 ± 1.0

W 3 17 ± 1.2 20 ± 1.2 17 ± 1.5

The value of fibre fineness is average value ± standard error.

2% 4%22 ±2.515 ± 1.0

6%25 ± 1.117 ± 1.2

changed by changing draft and cylinder speed of thecards to optimize it with a view to achieving optimumyam tenacity of bleached jute.

The unevenness of the finisher drawing sliver wasdetermined with an U ster evenness tester at a speed of25 m1rnin for 5 min after properly conditioning thematerial. The value of unevenness (U%) was convert-ed to CV/o (CV'Io = 1.25 U%) in accordance with theU ster Manual.

The spinning performance was studied by countingend-breaks for 10 doffs, the average breakage rate be-ing expressed as number of breaks per 100 spindle-hours.To improve the spinning performance, varioustwists per decimetre were tried during mill trials andfrom the corresponding yam test results, the opti-mum twist was determined for bleached jute.

The tensile strength of yam was determined bybreaking 100 pieces of single yarn on a Goodbrand'syam strength tester at a gauge length of 60cm with aconstant rate of traverse (30 cmlrnin). The lineardensity (tex) of the yarn was determined on the basisof 5 hanks of 67.5 meach from 5 different bobbins.The yarn tenacity (g/tex) was calculated by dividingthe average yam strength by its linear density.

The degree of whiteness was determined by mea-suring brightness index by using a reflection meter(Model No. CG-60 of Canadian Research Institute)with Tristimulus blue filters.

3 Results and DiscussionThe relationship between bundle tenacity of fibres

and concentration of H202 (Fig. 1) shows that thebundle tenacity decreases with increase in H202 con-centration. This is because the process reduces theamount of lignin, the main cementing agent for theconstituents". As a result, during carding, the weakerfibres break and the average fibre length decreaseswith increase in the concentration of H202 (Fig. 2).But fibre fineness does not change (Table 1) and thisimplies that H202 does not act uniformly on the fibresalong its length. The comparatively weak portion of it,where H202 acts directly, breaks during carding andturns into short fibres. The strong portion remains in-tact, resulting in the reduction in the average fibrelength but of the same fineness. The short fibres and

21r-----------------,

i 15uoc2!~ 10

3m

5'----'-- -'------'----':-------+---.----..'-;1023

'I. Concentration of H202

Fig. I-Relationship between bundle tenacity of fibres and con-centration of H202 [( x - x - x )TD3; (e-e-e) W3; and (0-

0-0)averagel

8r----------------,E

,;6r--~__r_-_____+___~I -~ ----~~4

6

Fig. 2- Relationship between average fibre length and concentra-tionofH202[( x - x=- x )TD3;(e-e-e)W3;and(0-0-0)

average)

Table 2-CardDropping(%)Card droppings at different cone. of

H202

0% 2% 4%

Breaker card 0.59 0.76 1.19Finisher card

Hlrtf-circular 1.21 1.29 1.43

(open)Full circular 1.06 1.12 1.28

(closed)

dust thus generated during carding drop under thecards as droppings which increase with increase in theconcentration of H202 (Table 2). The dust and shortfibres should be dropped to the extent possible,otherwise there would be a disturbance in the subse-quent processing, resulting in excessive slub in sliverand yarn. In this regard, open cards (half circular fin-isher card) appear to be better than closed cards (fullcircular finisher card).

37

INDIAN J. TEXT. RES., VOL. 12, MARCH 19,

With a view to achieving a gentler mechanical treat-ment of the tender bleached fibres during mill trials,carding intensity was gradually reduced from 4 x 103

to 2.4 X 103 by reducing the draft as well as cylinderspeed of a breaker card machine. The correspondingyam tenacity values (Table 3) show that a carding in-tensity of less than 3 x 103 improves yarn tenacity.Normally, carding intensity for jute cards varies be-tween 4 x 103 and 5 x 103.

Owing to the generation ofshort fibres during card-ing, the finisher drawing sliver unevenness (CV%) in-creases with increase in the concentration of H202(Table 4).

These results show that spinning performance de-teriorates with increase in the concentration ofHz02•

A few changes in the spinning parameters, specially inspeed (flyer rpm) and twist, were, therefore, found es-sential during trials. The spinning breaks per 100spindle-hours at various speeds ranging from 3600 to4200 rpm of slip draft (SD) spinning frames and from4000 to 4400 rpm of apron draft (AD) spinningframes for yarns of tex 235 to 345 against 0 to 4% con-centration ofH202 are shown in Fig. 3. Up to 4% con-centration of H20Z, AD frames with 4400 rpm andSD frames with 3600 rpm pose no problem for apaired frame spinner (one spinner looks after twoframes), since the breakage rate though higher re-mains within his piecing capacity 7. A higher twist wasessential (discussed later). The problem starts withthe high speed (4200 rpm) SD frames for 278 tex yamat higher (above 3%) concentrations of HzOz. Thehigh speed SD frames are single frames (one spinnerlooks after one frame) and the spinner has the scope ofmanaging a higher number of end-breaks per 100spindle-hours. Fig. 3 shows that up to 3% concentra-tion of HzOz end-breakage rate is within the piecingcapacity of the spinner but above 3%, the end-breaksgo beyond the control in spite of a higher twistbeing used.In this case a speed of 3800 rpm was found optimum at4% concentration of HzOz for 278 tex yam. Bleachedjute of these grades above 4% concentration of HzOzloses strength substantially and fails to achieve a satisfac-tory spinning performance at the normal speeds of thespinning frames mentioned above, i.e.fibre strength goesbelow the spinnability limit. A higher grade of jute(TD2) was spinnable at 6% concentration of H20Z'

Yam tenacity reduces gradually with increase in theconcentration ofHzOz up to 3% and above this thereis a rapid fall (Fig. 4). This trend accords with thespinning performance (Fig. 3). Hence it is clear thatthe bleached jute starts losing its spinnability rapidlyabove 3% concentration ofH20z, which correspondsto a bundle tenacity of 14 gltex (Fig. 1) and completelyloses spinnability above 4% concentration of HzOz,corresponding to a bundle tenacity of 13 gltex. This

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Table 3-Effect of Carding Intensity on Yarn Tenacity of276 texYam at 4% Cone. ofH202

Carding intensity

2.4 X 103 2.7 X 103 3 X 103 4 X 103

Yarn 9.23 ±0.16 9.1O±0.15 8.45 ±0.20 8.39±0.17tenacity,gltex

The value of yarn tenacity is average value ± standard error.

Table 4-Effeet of Cone. of H202 on Finisher DrawingSliver Unevenness

Parameter

0% 2% 4%Linear density of sliver, ktexUster CV'/o

4.2 4.5 4.310-12 13-15 15-17

~0r---------------------~

• 200J L......---

·l.&.,o5?,·i 100., 1-------

•

o 123

(')W Concentrottanot Hz 014

Fig. 3 - Relationship between spinning breaks and concentrationofH202(a-278 tex yam through SD frames at4200rpm;b-345texyam through SDframes at 4200 rpm;c - 278 tex yam through ADframes at 4400 rpm (X - through SD frames at 3600 rom); and

d - 235 tex yarn through AD'frames at 4000 rpm)

z.,------------------------,

20t.l~ ..;'0 ~

,I~-'----I. _--' -'---(%) ConClntration of HeOI

Fig. 4 - Relationship between yarn tenaci~ and concentration ofHZ02[( x -x- x )345tex;(0-0-0)278tex;and(e-e-e)

235texl

DATTA et al.: SPINNABILITY OF JUTE FIBRES

10

"s9 •

":. ••...o

~

ccz 8::0>-

17 "6 18'4

• •

19 '2

Twist/dm

20 20'8

Fig. :; - Effect of twist/drn on yam tenacity

indicates that jute fibres of tenacity below 13 Wtexcannot be spun with the conventional speed of thespinning frames under the paired and single frameoperation systems of the industry.

As mentioned earlier, a higher twist was foundnecessary to improve the spinning performance. dur-ing trials. This is because of the fact that ~horter ~bresrequire a greater cohesive f?r~e to achi~ve a higheryam tenacity. In order to opnnuse the twist of 278 t~xyam with 4% concentration of H202, yam tenacitywas evaluated for twists ranging from 17.6 to 20.8 perdrn; the results are shown in Fig. 5. The normal valueof twist is 16.8/dm. The figure shows that yam tena-city attains its maximum value correspond~g to 18.4twist/dm. For a lower degree of bleached Jute a pro-portionately lower twist was found optimum forprac-tical purposes, namely 18 for 3%, 17.6 for 2%, and soon. .

Measurements of the brightness index of raw Juteand fabrics with 4% bleached jute have shown that thebrightness index of raw jute varies between 25 and 27and that offabrics between 45 and 52.

4 ConclusionUp to 3% concentration ?f H202 ~e~e is no prob-

lem in spinning; only a higher twist IS necess~ry.Above this, a gentler carding is desirable and cardmgintensity ofless than 3 x 103 produces a stronger yam.At this stage, open finisher cards are preferable to

closed cards to reduce short fibres (%) in the sliver.Optimum flyer speeds are 3600 rpm and 3800 rpmfor paired frame and single frame operations of SDframes .

The loss in spinning productivity gradually in-creases with increase in concentration of H202• Inspite of this loss in productivity,the process is econ-omical because of its advantages like (i) minimumweight loss, (ii)no capital investment for wet-process-ingmachinery, (ill) no restriction on fabric width, and(iv) no extra labour/inputs of electricity/water andsteam as required in wet-processing.

The spionability of jute depends mainly upon thebundle tenacity of fibre and the limiting value is 13gltex.

Efficient spinning of weak fibres requires a highertwist and for 278 tex yam from fibres of bundle tenac-ityofas low as 13gltex,a twistof18.4/dmisoptimum.

AcknowledgementThe authors acknowledge with thanks the manage-

ments of Mis Champdhany Jute Co. Ltd, NuddeaMills Co. Ltd, Reliance Jute & Industries Ltd andAnglo India Jute Mills Co. Ltd for their cooperation inarranging trials in their mills. Thanks are due to Dr AK Mukherjee, Head, Applied Chemistry Division,and Shri A KMitra, Head, Mechanical Processing Di-vision, for their valuable suggestions and to Dr S RRanganathan, Director, DIRA, for permission to publishthe paper.

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Colourage, 32 (19)( 1985) 17.2 Indian standard specijicationsIS: 271 (Indian Standards Insti-

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24.5 Mather J N, Carding of jute and similar fibres (Iliffe, London)

1969,36.6 Guha Roy T K, Mukhopadhyay A K and Mukherjee A K, Text

ResJ, 54 (1984) 874.7 Datta U, Indian Text J, 88 (1978) 98.

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