Salt & alkali free reactive
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Salt & alkali free reactive Salt & alkali free reactive Document Transcript

  • Presented By: Salt & Alkali Free Reactive Dyeing On Cotton By: R. Nithyanandan and M. Subramanian Senthil Kannan
  • Presented By: Salt & Alkali Free Reactive Dyeing On Cotton By: R. Nithyanandan and M. Subramanian Senthil Kannan ABSTRACT In conventional Method of dyeing of cotton with reactive dyes, alkali P H is should maintain in the dye bath. This method requires more electrolytes for exhaustion and alkali for fixation. In this paper the fibre modification technique based on polyacrylamide was discussed. When the fabric is treated with polyacrylamide, the primary hydroxyl groups of cellulose is (partially) modified into a amide groups, which intern leads the cellulose to act like as wool fibre and hence reactive dyes can be dyed on cotton at neutral PH in the absence of electrolyte and alkali. INTRODUCTION In current practice, cellulosic fibres are predominantly dyed with reactive dyes in the presence of a considerable amount of salt and fixed under alkaline conditions. However, dye fixation efficiency on cellulosic fibres is generally low (varying from 50 – 90%). This, results in a highly coloured dye effluent, which is unfavorable on environmental grounds. Furthermore, the high concentrations (40 – 100g/I) of electrolyte and alkali (5 – 20 g/I) required in cellulose fiber dyeing may pose additional effluent problems. In this work, a new fiber –modification technique based on cationic acrylic copolymer. Pretreatment of cellulosic fiber with Polymer is believed to offer an opportunity for increasing both the substantivity and reactivity of fibers towards reactive dyes under neutral conditions. The nature of a reactive polymer resin is such that it may react with nucleophilic sites in cellulosic fibers or in the polymer itself, thus fixing the polymer to the substrate. During subsequent dyeing, further reactions between the polymer and the dyestuff, the fiber and the dyestuff, and the fibre and the polymer and can be expected to take place, forming crosslink within the fibers. MATERIALS AND METHODS: MATERIALS: Plain fabric of count 32 of warp and weft is used throughout the process. The weight of the fabric is 123 GSM, its cover factor is 21.63, and Ends/inch is 98, Picks/ inch is 64. Were Polyacrylamide resin, reactive dyes, Remazol Brill.Orange 3 R, Remazol Brill.Red 5B, Remazol Brill.Violet 5R, Remazol Turquiose Blue G, Procion Red M5B, Cibacron Green LS – 3 B, Cibacron Navy LS – G, Cibacron Red FN – R Cibacron Yellow FN – R are used. METHODS: The material is first Desized using enzyme, scoured with caustic soda and then bleached with hydrogen peroxide. The fabric neutralized and goes for dyeing. DYEING CONVENTIONAL METHOD: The dye bath is set with calculated amount of dye solution and water using MLR 1:20. Enter the wetted well bleached fabric into the bath, raise the temperature to 40o c and work for 10 min then add the calculated quantity of salt in three portions at regular intervals (10 min). Raise the temperature to 50 o c and continue dyeing for 30 min, add the calculated quantity of soda ash and continue the dyeing for further 30 min. Finally take the material out, wash the material with cold water and then give soaping treatment to remove the unfixed dyestuffs and chemicals. The dyeing temperature and recipe of various reactive dyes are shown in table 1
  • Presented By: Table no: 1 Note: Incase of vinylsulphone reactive dyes neutralization is very important before soaping. Neutralization is carried out with 0.5% Hcl at room temperature. FIBRE MODIFICATION TECHNIQUE Treatment with polyacrylamide: Pad the material with calculated quantity of polyacrylamide and water with 70% expression. After padding the material is dried at ambient temperature and then cured at 120o c for 7 min. Dyeing of pretreated fabric: Set the bath with calculated amount of dye solution and water. Enter the pretreated fabric into the bath. Raise the temperature to a specified level at 1.5o c / min, and dyeing continue at the set temperature for the further 60 min. Finally take out the material, soaped thoroughly and washed with cold water and dried. RESULTS: Determination of fastness to washing: The wash fastness was tested following ISO (standards) test no: 2 Table 2: Wash fastness values. Determination of fastness to light: The light fastness was tested following ISO (standards) test no: 2 Table 3: Light fastness values. S.No Dyes Salt Dyeing Temperature Soda ash 1 2 3 4 DCT Vinylsulphone Cibacron Ls Cibacron Fn 50 g/l 50 g/l 25 g/l 50 g/l Room temperature 60o c 70o c 60o c 15 g/l 15 g/l 7 g/l 15 g/l Dye stuff C.I Reactive Untreated Treated Remazol Brill.Orange 3 R Remazol Brill.Red 5B Remazol Brill.Violet 5R Remazol Turquiose Blue G Procion Red M5B Cibacron Green LS – 3 B Cibacron Navy LS - G Cibacron Red FN – R Cibacron Yellow FN – R Orange 7 Red 21 Violet 5 Blue 21 Red 2 - - - - 5 5 5 5 5 5 5 5 5 5 5 4 - 5 4 -5 4 - 5 5 5 5 5
  • Presented By: Determination of colour strength (k/s): The colour strength which is a measure using spectrophotometer using KUBELKA – MUNK FUNCTION. K/S = (1 – R)2 /2R Where, R = Reflectance value at wave length of maximum absorption. K =Absorption co – efficient S = Scattering co – efficient Table 4: The colour strength values Dye stuff C.I Reactive Untreated Treated Remazol Brill.Orange 3 R Remazol Brill.Red 5B Remazol Brill.Violet 5R Remazol Turquiose Blue G Procion Red M5B Cibacron Green LS – 3 B Cibacron Navy LS - G Cibacron Red FN – R Cibacron Yellow FN – R Orange 7 Red 21 Violet 5 Blue 21 Red 2 __ __ __ __ 7 - 8 8 8 8 8 7 – 8 8 8 7 - 8 7 – 8 7 – 8 7 7 –8 8 7 – 8 8 8 7 - 8 Dye stuff C.I Reactive Dye conc. % Untreate d Treated Remazol Brill.Orange 3 R Remazol Brill.Red 5B Remazol Brill.Violet 5R Remazol Turquiose Blue G Procion Red M5B Cibacron Green LS – 3 B Cibacron Navy LS - G Cibacron Red FN – R Cibacron Yellow FN – R Orange 7 Red 21 Violet 5 Blue 21 Red 2 __ __ __ __ 1.0 2.0 3.0 1.0 2.0 3.0 1.0 2.0 3.0 1.0 2.0 3.0 1.0 2.0 3.0 1.0 2.0 3.0 1.0 2.0 3.0 1.0 2.0 3.0 1.0 2.0 3.0 7.76 11.56 14.86 8.69 13.98 21.45 6.89 12.52 15.93 6.96 14.12 17.86 15.06 19.77 20.25 14.78 19.06 23.06 11.79 15.86 18.95 15.06 20.03 24.12 13.93 18.79 20.03 8.03 12.11 15.12 9.82 15.03 24.03 7.79 13.97 16.03 7.72 14.98 17.98 16.77 20.80 21.03 15.62 19.98 24.02 12.34 16.04 20.01 15.94 21.12 25.98 13.98 19.56 20.68
  • Presented By: DISCUSSION: The probable mechanism for the fixation of reactive dye on the polymer treated cotton sustain may be expressed as follows: The pretreatment of cotton fabric with polyacrylamide demonstrates the introduction of functional amino groups which increase the substantivity and also the reactivity of cotton. The cationic charged amino groups may be involved in the adsorption of anionic chromophore of reactive dyes. Structure of polyacrylamide Reaction Cellulose Polyacrylamide The improved dye ability is postulated due to the presence of amide groups (-CONH2) available from the polyacrylamide which also tents to improve the reactivity of cellulosic substrate. The attachment of the dye molecules onto the partially-modified cellulosic substrate is by covalent bonding since no dyes strips out from the dyed sample. This is also indicative through the fastness properties wash fastness. The fastness values (given in table 1 and 2) of all such dyed samples are quite satisfactory and comparable with those of conventional dyed samples. The dry crease recovery angle values of the polymer treated samples are 80 o while that of conventional dyed sample is 68 o. Therefore, as expected, the polymer treated dyed samples indicate an improvement in the wrinkle recovery. A high level of dye exhaustion on the treated fabric can be achieve in the absence of salt and alkali at a temperature as low as (Normally at 60-80o c) that used in the conventional dyeing process. Further increases in temperature may improve dye bath exhaustion, but only to a limited extent. However higher temperatures (90-100 o c) are generally recommended for dyeing modified fabrics to obtain better penetration and fixation. CONCLUSIONS: Pretreatment of cotton with polyacrylamide enhances the possibility of dyeing cotton at neutral pH with various commercial reactive dyes. Such pretreatment, as applied through pad – dry – cure process, brings about some chemical changes in the treated fabric.
  • Presented By: Fastness properties are adequate and quite comparable with conventionally dyed samples. The wrinkle resistance of the dyed fabric also improves. The dyeing of cotton with reactive dyes using polyacrylamide in the dye bath improves the dye ability of cellulosic fabrics with reactive dyes and reducing effluent discharge. When dyeing the modified substrates, reactive dyes can be much more efficiently exhausted and fixed onto cellulosic fabrics under neutral conditions in the absence of salt. The modifications show an overall suitability for different reactive dyes. The modified dyeing do not suffer either from a significant drop in light fastness, wash fastness or from duller shades. REFERENCES: 1) Burkinshaw , S.M.,Lei,X .P., and Lewis, D.M. Modification of Cotton to Improve its Dyebility , Part I : Pretreating Cotton with Reactive Polyamide - epichlorohydrin Resin. J,Soc.Dyers Colour.105 (11),391 – 398 (1989) 2) Burkinshaw , S.M.,Lei,X .P., Lewis, D.M., Easton, J.R., Parton, B., and Philips, D.A.s., Modification of Cotton to improve its Dye ability, Part 2: Pretreating Cotton with a Thiourea Derivative of Polyamide – epichlorohydrin Resins, J.Soc.Dyers and Colours.106 (10),307 – 315 (1990) 3) Booth J.E, principles of textile testing, [Butterworth scientific publishers, London, 1987. 4) Bhattacharya S.D.& B.J Agarwal , A novel technique of cotton dyeing at reactive dyes at neutral pH , IJF & TR ,vol 26, Dec 2001, PP 418 - 424 5) Cai.Y, M.T.Pailthorpe and S.K.David , A new method of improving the dye ability of cotton with reactive dyes, TRJ (440 – 446). 6) Lewis, D.M.. New Possibilities to improve Cellulose Fibre Dyeing Processes with fibre- reactive systems:J .Soc.Dyers Colour .106 (11), 352 – 357 (1990). 7) Lewis, D.M.,and Lei, X.P., New methods of improving the dye ability of cellulose Fibres with reactive dyes, J.Soc.Dyers colour . 107 (3), 102- 109 (1991) 8) Texincon,vol 14, No 2, Page no 14.(World Textile Abstract) About the Author: M. Subramanian Senthil Kannan is presently working as a KAM Executive in Consumer Testing Services, SGS India (P) Ltd, Bangalore. He is a Textile Graduate from Bannari Amman Institute of Technology, Tamilnadu. He has obtained his master’s degree in Textile Technology from PSG college of Technology, Coimbatore, Tamilnadu. He is a gold medalist in both of his UG and PG programmes. He has published around 60 articles in various national and international journals. He has also presented many technical papers in various national level symposia and in various national & international conferences. He has won several prizes in paper & poster presentations and quiz competitions in both national and international levels. He has got one and half years of experience in R& D in spinning and weaving and one year in Quality assurance in Spinning. Email: