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Eco friendly dyes and dyeing procedure


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Eco friendly dyes and dyeing procedure

  1. 1. Prepared By : Mazadul Hasan sheshir ID: 2010000400008 13th Batch (session 2009-2013) Department : Wet Processing Technology Email: Blog : www. (visit) Southeast University Department Of Textile Engineering I/A 251,252 Tejgaon Dhaka Bangladesh Prepared By :
  2. 2. Total Textile Process at a Glance
  3. 3. Today, the textile industry, which uses on an average six hundred dyes and chemicals for the production of consumer textiles, is considered must polluting. With the kind of awareness and restrictions coming in to ecology of textiles world over, the first thing every textile processor need to know prior to processing any materials are the nature of end use of the textile being processed and the country which being exported. Because each end use, e.g. baby wear, clothing in direct contact with skin, furnishing fabrics etc. will have different specifications just as each country will have different legislation.
  4. 4. We are polluting our environment as well as destroying our world by using non eco dyes and chemical
  5. 5. • Prohibited amines • Chlorinated phenols • Formaldehyde • Extractable heavy metals • Residuals pesticides • Allergenic dyes • Chlorinated Benzenes & Toluene compound • Phthalates • Organo Tin compound
  6. 6. Because it create different problem: • Health Problems • Clothing dyes can cause the following health problems: • skin rashes • headaches • trouble concentrating • nausea • diarrhea • fatigue • muscle and joint pain • dizziness • breathing difficulties • irregular heart beat • seizures
  7. 7. •Furthermore, children can experience the following: •red cheeks and ears •dark circles under the eyes •hyperactivity •behavioral problems •learning problems Because clothing is in constant contact with your skin, the chemicals are absorbed into your skin through your pores. They can then enter your liver, kidney, bones, heart and brain. Most people have some sort of chemical sensitivity. Some are more sensitive to chemicals than others. Those who are more sensitive will notice the impact of clothing dyes more than others. Those of us who aren’t as sensitive, may still experience some symptoms but just not realize it.
  8. 8. A Dyeing process that is most suitable and within the norms of Eco labels standards is called Eco Dyeing.
  9. 9. Some of the useful tips all may consider are: • Select dyestuff that does not contain Chlorinated benzene and toluene. • Avoid using Carcinogenic dyestuffs in your combinations. • Avoid using Allergic dyestuffs (some selected disperse dyes are allergic). • Do not use chelating agents that contain phosphates. • Use APEO and NPEO free surfactants as dispersing agents. • Ascertain that your surfactant do not contain any ethoxylated products. • Use Formic acid for neutralization purposes rather than Acetic acid. • Do not use formaldehyde containing dye fixing agents after reactive/direct dyeing. • Use Natural dyes can be used and that does not have heavy metals etc, give the first preference.
  10. 10. • Most important is to control and limit the use of water for all purposes. • If reactive dyeing is carried out, where ever possible go for low salt and no salt dyeing/trials. • Avoid reprocessing, save energy, money and water. • Try and establish a system of Right First Time practice in dyeing. • In reactive dyeing, where ever possible you may try cold dyeing to save energy. Preconditioning method is one such procedure. • In disperse dyeing avoid using phenolic carriers. Select dyestuffs carefully. • In wool and silk dyeing metal complex dyes' selection should be optimistic. • In all cases of wet processing, establish a suitable system of water recycling either with an R.O.system or Nano System.
  11. 11. Government Eco-Labels Commercial Eco-Labels Eco mark – Japan Oeko Tex 100 – Germany/ Austria Green Seal – USA Tox Proof – TUV, Germany Flower – EU GuT – Carpets, Germany Different country maintain different Eco-Labels
  12. 12. No Eco parameter Permissible limits 01 Presence of banned amine <30 ppm 02 Presence of pentachlorophenol(PCP) <0.5 ppm (Baby wear : <0.05 ppm) 03 Presence of formaldehyde <300 ppm - material not in direct skin contact, <75 ppm – material in direct skin contact, <20 ppm – baby wear. 04 Presence of heavy metals* Customer specific 05 Residual pesticides <1.0 ppm (Baby wear 0.5 ppm) 06 Allergenic dyes Not to be used 07 Carcinogenic dyes Not to be used 08 Chlorinated benzene & Toluene <1.0 ppm 09 Presence of Phthalate <0.01 ppm 10 Organic Tin Compounds <1.0 ppm 11 pH value of Aqueous Extract Should be nearly neutral (pH -4.5 to 7.5) 12 Color fastness As per specification Typical eco-parameters under the Eco-labels for finished textiles are,
  13. 13. CRITERIA FOR ECO-LABELS Product based Process based
  14. 14. Environmental Regulation • Oeko—Tex standard, • REACH, • GOTS, • Bluesign • EU Eco Label • Made In Green • Made By
  15. 15. Product based Pertains to the limits of harmful chemicals which vary with the intended use of textiles. • Group 1 Baby wear, the limits are the lowest (stringent) for the cloths and textiles for babies below age 3. • Group 2 Material in direct skin contact, worn next to skin, for example – underwear, bed sheets and night dresses etc. • Group 3 Materials are not in direct skin contact. Textile worn as second layer dresses, coats, articles with linings. • Group 4 Furnishings articles and accessories for decorative purpose. e.g. table wear, upholstery, curtains, textiles flooring and mattresses.
  16. 16. • These are recommendations for processes to be avoided such as • Bleaching with hypochlorite. • Use of chlorinated organic compounds as carriers in dyeing of polyester • Optimum use of water and energy. • Dyestuffs when exhausted on fiber are fixed only to the extent of 50- 90%, the un-exhausted dye with chemical impurities contaminate the effluent, hence there is a need to ensure that dyestuff and dye additives that go in to the dyeing process are eco friendly. • Ecological norms for the dye are considered assuming it’s concentration up to 10% on textile and 2% dye diluted to 1:2500 in effluent. • Fastness properties (washing and rubbing dry/wet) of dyes on finished textiles also form part of eco norms considering their possible transfer on the skin. Process Based
  17. 17. Any of a class of colored, water soluble compounds that have an affinity for fiber and are taken up directly, such as the benzidine derivatives. Direct dyes are usually cheap and easily applied, and they can yield bright colors. Wash fastness is poor but may be improved by after treatment. Most packaged dyes sold for home use are direct dyes.
  18. 18. Direct dyes are also called substantive dyes because of their excellent substantively for cellulosic textile materials like cotton and viscose rayon. This class of dyes derives its name from its property of having direct affinity for cellulosic fibres, when applied from an aqueous solution.
  19. 19. • Solubility in water. • Affinity to cellulosic fiber. • Easy penetration • Washing fastness are not good enough • It is applied in neutral as alkali medium • Cheap • This dye does not react with fiber. But create H-bond R N H-----------O cellulose A H Direct dye • Chemically, direct dyes are sodium salts of aromatic sulphonic acids and most of them contain an azo group as the main chromophore. They are in general duller than the fiber reactive dyes, and exhibit poor wash fastness. Goods dyed with direct dyes unless; given a proper after treatment tend to bleed with every wash. The direct dyes in many cases exhibit a better light fastness as compared to the reactive dyes. Properties of Direct Dyes:
  20. 20. Vat dyes are an ancient class of dye, based on the original natural dye, Indigo, which is now produced synthetically. Both cotton and wool, as well as other fibers, can be dyed with vat dyes. Not all vat dyeing is done with vat dyes! "Vat dyeing" means dyeing in a bucket or vat. It can be done whenever a solid even shade, the same color over the entire garment, is wanted, using almost any dye, including fiber reactive dye, direct dye, acid dye, etc. The opposite of vat dyeing is direct dye application, such as, for example, tie dyeing. Vat dye
  21. 21. Most vat dyes are less suitable than, say, fiber reactive dyes, for the home dyer, as they are difficult to work with; they require a reducing agent to solubilize them. The dye is soluble only in its reduced (oxygen-free) form. The fiber is immersed repeatedly in this oxygen-free dye bath, and then exposed to the air, whereupon the water-soluble reduced form changes color as oxygen turns it to the water- insoluble form. Indigo is an example of this dye class; it changes from yellow, in the dye bath, to green and then blue as the air hits it.
  22. 22. • Vat dye, being insoluble in water, cannot be directly applied to textile materials. They have to be converted into their water soluble form, having affinity for textile fibre such as cellulosic fibres. This conversion is usually brought about in two steps, • Reduction of the dye into the weakly acidic leuco vat form and • Salt formation by neutralizing these acidic leuco vat dyes by sodium hydroxide to give a water soluble product. • Since the second step result in the formation of water soluble sodium salt of the leuco vat dye it may be called the solubilising step. Reduction followed by solubilising is called vatting of the dye. For this purpose sodium hydrosulphite Na2S2O4( usually called hydros) is used as the reducing agent and sodium hydroxide as the solubilising (neutralizing ) agent. Properties of vat dye:
  23. 23. They tend to be fairly hydrophobic (though this depends on the structure of R1 and R2), but not as much as, say, a long hydrocarbon would be, since the -COOC- groups cause some polarity. The polymer chains in a sample of polyester are highly crystalline (for a polymer) and quite tightly packed together. The result of this is that polyesters have very little affinity for large ionic dyes- the dyes simply cannot either distribute between the chains, or form satisfactory intermolecular interactions. Therefore, acid and direct dye classes are useless for this polymer. Disperse dyes have low solubility in water, but they can interact with the polyester chains by forming dispersed particles. Their main use is the dyeing of polyesters, and they find minor use dyeing cellulose acetates and polyamides. The general structure of disperse dyes is small, planar and non-ionic, with attached polar functional groups like -NO2 and -CN. The shape makes it easier for the dye to slide between the tightly-packed polymer chains, and the polar groups improve the water solubility, improve the dipolar bonding between dye and polymer and affect the color of the dye. However, their small size means that disperse dyes are quite volatile, and tend to sublime out of the polymer at sufficiently high temperatures. The dye is generally applied under pressure, at temperatures of about 130o C. At this temperature, thermal agitation causes the polymer's structure to become looser and less crystalline, opening gaps for the dye molecules to enter. The interactions between dye and polymer are thought to be Van-der-Waals and dipole forces. The volatility of the dye can cause loss of color density, and staining of other materials at high temperatures. This can be counteracted by using larger molecules or making the dye more polar (or both). This has a drawback, however, in that this new larger, more polar molecule will need more extreme forcing conditions to dye the polymer. Disperse dyes
  24. 24. • Non soluble • Non ionic • Molecularly disperse • Used for manmade fibre dyeing ex-polyester, polyamide fibre. • Hydrophobic textile material dyeing. • Fair to good light fastness (4-5) • Color fastness, wash fastness (3-4) Properties of disperse dye:
  25. 25. REACTIVE DYE Unlike other dyes, reactive dye actually forms a covalent bond with the cellulose or protein molecule. Once the bond is formed, the dye molecule has become an actual part of the cellulose fiber molecule. No wonder you can safely wash a garment that has been dyed in bright fiber reactive colors with white clothing, a hundred times, without endangering the whites in the least - even if it is all different bright colors, or even solid black! The official definition of a "fiber reactive dye" is provided by Rys and Zollinger in chapter VII of their book, The Theory of Coloration of Textiles (1975) from the Dyers Company Publications Trust, England. A fiber reactive dye "is a colored compound which has a suitable group capable of forming a covalent bond between a carbon atom of the dye ion or molecule and an oxygen, nitrogen, or sulphur atom of a hydroxy, an amino or a mercapto group respectively of the substrate." They point out that the definition excludes mordant dyes and 1: 1 chromium azo dye complexes which, in dyeing protein fibers may form covalent bonds between metal ion and nucleophilic groups of the fiber. What all this means is that a fiber reactive dye reacts to form a true bond (not just a plus or minus charge attraction or an entrapment in the fiber) with the fiber involved. In the case of cellulose the bond is with the hydroxyl (-OH) groups present in vast numbers on the cellulose molecule and in the case of protein fibers with the amino (-NH3 ) group present on the protein molecule.
  26. 26. • Reactive dyes are highly soluble in water. • Dye creates on covalent bond with fiber. • Reactive dye can be used for dyeing cellulosic cotton, wool nylon. • Fixation occurred in alkaline solution. • Reactive dye can produce all types of shades. • Dyeing method is easy for reactive dye. • Light fastness is very good; rating 6 out of 8. • Wash fastness is also good (rating: 4-5). • Fixation occurred in alkaline solution. Properties of reactive dye
  27. 27. The dyeing principle is based on fiber reactivity and involves the reaction of a functional group of the dyestuff with a site on the fiber to form a covalent link between the dye molecule and the substance. The Four structural feature of typical reactive dyes molecule are: • 1. The chromophoric grouping, contributing the color • 2. The reactive system, enabling the dye to react with hydroxy group in cellulose. • 3. A bridging group that links the reactive system to the chromophore. • 4. One or more solublising group, usually sulphuric acid substituent attached to the chromophoric group for their color, although the azo chromophore –N=N- is by itself the most important. All the reactive dyes contain sodium sulphonate group for solubility and dissolve in water to give colored sulphonate anions and sodium cations. Most reactive dyes have one to four of these sulphonate group, General form of reactive dye is as follows: S------R----B----X Where, S = Water solubility group R = Chromophore X = Reactive System B = Bond between reactive system and Chromophore Mechanism of Dyeing
  28. 28. Natural Indigo Madder Lac Catechu Pomegranate Kamala Mayrabolan Himalayan Rubrub Natural dye Extract From This plant
  29. 29. Natural indigo
  30. 30. Naturally colored cotton
  31. 31. Natural Dye
  32. 32. Natural Dye
  33. 33. Natural Dye
  34. 34. Airflow Dyeing MachineAirflow Dyeing Machine
  35. 35. Evaporate Curve Gas
  36. 36. 1. Yarn Manufacturing Technology Link : Technology/485014954866808 2. Fabric Manufacturing Technology Link : Technology/459520217425605 3. Garments Manufacturing Technology Link : Technology/472364799463126 3. Wet processing Technology Link : Dyeing-/468645219825404 4. Fashion-Design-and-Technology Link : Technology/587655294583875?ref=ts&fref=ts My Facebook Textile related Pages (Visit My Blog for more Info )