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by K.G.Mohanan, P.C.Antonel Vaz, J.Sunilduth, A.Radhakrishnan, V.A.Sebastian and U.S.Sarma, Proceedings of
the International workshop on Wet processing of Coir 8-9, December 1997
Dyeing of coir
fibre/yarn is essential for improving the marketability of coir products and
satisfying the requirements of consumers. A literature and industrial survey had
been conducted to ascertain the dyestuffs/chemicals and processes used for
colouring coir materials and comparative cost involved for dyeing of coir. The
fastness characteristics of different classes of dyestuffs used for dyeing of
coir materials were analysed and chemicals marketed by different firms were
examined for their suitability in the dyeing of coir.
The synthetic, natural and ecofriendly dyestuffs were identified and
dyeing experiments were carried out for assessing their suitability to coir.
A dyestuff is
most commonly an organic compound which can be used to impart colour to a
substance. The literature survey
reveals that a wide range of dyes capable of yielding bright shades of good to
excellent fastness are available for the dyeing of textiles.
However, quite a large number of such dyes are not useful for dyeing
coir, for some of them require special pretreatments of the material before the
dye is applied or they are costly from the point of view of the coir industry. Dyes are applied
to coir materials by two distinct processes, dyeing and printing of which the
former is extensively used. In
dyeing, the fibre absorbs the dye from the aqueous solution or dispersion and is
more or less uniformly coloured. The
uniformity of dyeing (level dyeing) depends upon the absorptive power of coir
fibre, the nature of the dye and condition of dyeing.
The dyed shade usually must be matched against a sample and the fastness
of the dyeing (ie. the resistance of the shade to the action of light, water
rubbing etc.) must conform to the specified requirement of the consumer. In the attempts
to identify dyes/chemicals suitable for achieving better fastness properties,
penetration and brilliant shade with less cost revealed that the most commonly
used dyestuffs for coir materials belong to the classes of Basic, Acid and
Direct dyes. These dyes are applied
to the materials from their solution in water with the aid of chemicals like
acetic acid, sulphuric acid formic acid, common salt etc. to facilitate the transfer of dyes from the dye bath to the
fibre substrate under appropriate conditions of temperature for specified
periods depending on the dyestuff that is being used. The basic dyes
have high tinctorial value and affinity to coir but are fugitive to light and
rubbing. The acid dyes have better
fastness to light but of less brightness that basic dyes.
Direct dyes find use in producing shades having fastness properties
better than acid dyes but they produce dull shades and require longer processing
time. The use of imported dyes is
limited in coir Industry.
The survey
confirmed that the major quantity of dyeing of coir fibre/yarn is done in the
small scale sector using conventional process.
With a view to improve the quality of dyed material, modern dyeing
methods are also adopted by the industry. The
industry adopts the following methods for dyeing. 1.
Conventional method of dyeing coir 2.
Improved method of dyeing coir 3.
Mechanised method of dyeing coir In the
conventional method, the dyeing is carried out in copper or alminium/Indalium or
G.I dye vat of 1.2 M dia and 0.75 height placed on hearth made out of country
bricks, fired from below using country wood.
The dye vat is sufficient to process 60 kg.of coir yarn or 30 kg.of coir
fibre with a material to liquor ratio of 1:12 for coir yarn and 1:20 for coir
fibre. After filling with required quantity of water, it is heated from below
till the required temperature is reached. The
required quantity of dyestuffs (according to the percentage of shade) and
chemicals are added to the dye bath after making into a paste. The dye bath is
stirred well and the material is entered and turned manually at frequent
intervals for level dyeing. At the
end of dyeing the material is taken out washed in cold water and dried under
shade. IMPROVED
METHOD OF DYEING COIR The improved
method of dyeing process is carried out by highly skilled ‘Moopans’in the
industry using dye vats made or stainless steel and fitted with drinage valve
for proper draining or dye effluents. The
vats are fixed on hearths made of fire bricks with flue pipes for efficient air
draught for maximum utilisation of the heat energy. The dyes are taken as per
recipes formulated by CCRI which is available on the shade cards.
The quality of dyeing is improved compared to the small scale sector. MECHANISED
SYSTEM OF DYEING To get the best
desired result, coir yarn is dyed in the mechanised system of dyeing, comprising
of dye vats with forced circulation of the dye liquor in two directions on
uniformly arranged coir yarn for uniform level dyeing. The temperature is
controlled as per the requirement by regulating the flow of heating system.
After the dyeing operation, hydro-extractors are used to drive out the
major part of the machanically held up water and finally these materials are
dried on the endless conveyor drier, for efficient drying.
This system of dyeing helps to improve the penetration, shade
consistency, uniform dyeing on coir fibre/yarn by the action of temperature,
efficient & forced circulation of dye liquor and period of dyeing.
This method help to dye large quantities of material at a time avoiding
shade variations compared to the other two processes. The comparative
cost for dyeing using standard receipes for five common solid colours in
conventional improved and mechanised system of dyeings are furnished below as
Table –I
The
fastness properties of dyed coir materials witch as water fastness, light
fastness and rubbing fastness, are to be determined in respect of each dyestuff
belonging to the different classes. A
number of dyestuffs belonging to basic, acid and direct classes were used to for
colouring coir materials such as retted coir fibre, green husks fibre, green
husk treated with coirret, yarn from retted and brown coir fibre.
The details of the shades developed with receipe are furnished as
Annexure-1I The yarn
produced from brown fibre was dyed in different shades using dyestuffs such as
Auramine, Rhodamine B 500, Magenta, Malachite green, Bismark brown, Chrysodine,
Methyle violet at different concentrations of 0.2%, 0.25% and 0.3%. It was observed
that the shades with 0.25% of the basic dyes showed a satisfactory coverage on
the fibre. In order to
compare the brightness of shade, pick up light and water fastness, green husk
fibre treated with coirret and retted coir fibre were dyed using Acid orange II,
Rhodamine B 500, Direct green B and Malachite green for developing different
shades. 4 shades evolved
from acid and 2 shades from direct classes of dyestuffs which is safe to the
environment was taken on coir yarn spun from retted fibre using receipe.
Detailed in Table VI
1.
The mechanised system
of dyeing is most effective as it helps to achieve shade consistency, between penetration of dyes and byulk treatment of odye effluent 2.
The list of banned
carcinogenic dyes and chemicals were identified and circulated
among the trade. 3.
It is desirable to assess fastness properties of each dyestuff belonging
to different classes and their suitability to coir 5. Strict adherance to the methods of dyeing including the optimum use of chemicals, temp and duration of treatment is necessary
to obtain dyeing of satisfactory standards. 7.
Light bleaching of the material prior to dyeing yield pastel shades of good
brightness.
The authors
place it on record their sincere thanks to FAO/CFC for providing fund to conduct
the studies and also grateful to the Coir Board for providing facilities for
carrying out the investigations and for their kind permission to publish this
paper,
BIBLIOGRA 1. Reactive dyes
toxicity, V.A.Shenai, Chemical Weekly, May 9, 1995 P 151 2. Toxicity of
dyes oand Intermediates, V.A.Shenai, Chemical Weekly, March 28,
1995
3. Dyestuff
Industries in a changing Era-Chalenges and oppurtunities, R.A.Mashelkar
and T.Ravindran, Chemical Weekly July 25
1995 P 147-151 4. “German
Ban” An Eco Friendly Prescription for the coir Industry, U.S.Sarma
Coir News Vol-24, Book5, May 1995,P 25-37 5.Treating of
sisal and hard fibre, H.A.Elkin and W.A.S.White, C.A.Vol 36, 1942
P
5029-5030 6.Dyeing of jute
and hesian fabrics, J.W.Brown, C.A.Vol.37, 1943, P 1043-1044 7. Coir dyeing,
K.K.Kylas, C.A.Vol.39,1945 P.623-624 8. Absorption of
basic dyes on jute, P.B.Sarkar, et-al, C.A.Vol –40, 1946, P 4857-
4788. 9. Action of light upon
Jute,H.J.Callow,C.A.Vol.41, 1947,P 4651-4652 10. Coir observation and it dying
characteristics, G.N.Prabhu, Coir, Vol 5, 1961,3,
P.25-27 11. Staining jute by different acid and
role of lignin BC.Chatterjee ann S.N.Bose,
C.A.Vol.68,1968,P 201-203 12. Dyeing Sisal and other plant fibre,
AJ Canning and C.G.Jarman, G 177
Nov.
1983, TDRI, London. 13. Black dyes for coir fibre,
A.J.Canning and C.G.Jarman, 1, 40 1979, TDRI, London 14. Dyeing leaves and straws,
A.J.Canning and C.G.Jarman G. 178 1983
TDRI, London 15. Dyeing Sisal and other plant fibre,
A.J.Canning and C.G.Jarman, G.178,1983
TDRI, London. 16. Dyeing Studies at elevated
temperatures between 200 and 300 deg.F.Heat,G..I Reyer
et.al.C.A. Vol 43, 1949, P 1904-1905 17. Dyeing of Textile fibre at high
temperature, L.Drijvers Teintex C.A.Vol 46,
1952, P.6865-9892 18. Application of dyes to textile
fibres at high temperature, Charles. L.Zimmerman
C.A.Vol.48,1954, P 627-634 19. Dyeing cellulose fibre at a
temperature higher than 100 deg.cent. J.G.S.
Pawelstia,C.A..vol 60, 1964, P 3461-7420 20.Treating of jute for improved light
fastness. Sengupta et.al.CA Vol 72,
1970, 676223 21. Action of light on jute, W.G.
Macmillan et.al. J.Text. Inst. 45 1954,
P 700-702 22. Dyeing on sisal and other plant
fibres, A hand book for craft instructors,
A.J.Canning & C.G.Jarman. G 176, 1983,
TDRI, London 23. Light fastness of dyeing, the state
of direct dyes in cellulose, Wanshikha Ta Hanhua Hsueh Hui-chit, C.A.Vol.60, 1964, P
3460. 24. High light fastness of dyes,
C.H.Giles and K.V.Datya, J.App ;.Chem,
C,.A..Vol.60, 1964, P 473 25. Xenon 450, an apparatus for rapid
illumination and weathering, Kockott, Dieter
Klippert, C.A.Vol.70, 1969, P.1692, 479 zq. 26. Colour change due to flart abrasion
(Frosting) Screen method AATCC
technical manual
1963. 27. Colour fastness to crocking carpets,
AATCC Test method 165, 1988AATCC
Technical Manual 1993 28. Colour change due to flat abrasion
(Frosting) AATCC Test method 120, 1989
Emery mothos, AATCC Manual 1993 29. Silk and wool with
god colour fastness to
rubbing Sawa, Masad , Yasube,
Kazuo, Tapan, C>A>Vol.73, 1970 P 21136. 30. Technology of Textile
Proscessing V.A.Shenai (UDCT,
Mumbai, India)Textile
dyer Printer, C.A. Vol.73,1970,P67529. 31.
High Temperature Dyeing .P.K.Agrawal.
Silk & Rayoon Industries
. India C.A.Vol.73, 1970. P
83662. 32. Coir Dyeing K.Kylash, C.A.
Vop.139,1945.P1261 33. Dyeing
of Jute Hessuab Favbric
A.W.Brown, Text, Journal Australia,.
XC.A.Vol.37. 1969, P1043-1044. 34. Silk Rayon Industry in India ,
M.D.Bhavsar, Sasmira, Mumbai India
C.A.Vol.71,1969,P113982 35. Mechanised cor dyeing , K.G.Mohanan,
Coir News, Vol XXIV No.3 March
15 1995 P9 36. Levelers for Dyeing, Sara P Malik,
Belgium, C.A. Vol 61, 1964, P 16472 37. Effect of light on dyeing and dyes,
Ludwig, Hoffmann, V.A.Vol 61, 1964, P 12597 38. Dyeing of cotton with reactive
dyes. H.T.Lokhande, C.A.Vol.71,1969, P.3699 39. Dyeing of cellulose fibres with
reactive dyes, Vonder Eltz, C.A.Vol 74, 1971,
P 14147. 40. Basic Dyes in Textile Printing,
Kuchnel, C.A.Vol 72, 1970 P.101671 41. Application of textiles
auxiliaries, Nirokas. M.V.Chem.Abstr.74, 1971,
P.134845 42. Blue colour fading of the ISI light
fstness scale in relation to the amount of
irradiated light. Presle L F C, Chem 74,
1971 P 49466 43. Dyeing and Printing with fibre reactive dyes.
Balland Jean,
Chem.Abstr
74, 1971, P 14152 44. Technology of Textile Processing, Shenai. V.A. Chem.Abstr.72, 1970,P,137184 45. Brightness and Uniformity of dyeing
from the view point of the dyeing material Fujimoto
Nubumasa, Chem.Abstr.73, 1970 P.105258 46. Simultaneous bleaching and dyeing
of cellulose fibre by means of indigosol, Goorhuls,
Chem.Abstr. 69, 1968 P.11317 47.Singlebath bleaching-dyeing of jute
fabric with hydrogen peroxide-direct
dyeing combinations. Pandey S.N.,
Chattopadya A.N, Pan N.C. and Dey A. Indian
Journal of fibre & Textile Research Vol.19, March 1994 P.3437 ANNEXURE-1
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