Reactive Dyes

Reactive Dyes

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  BGMEA University ofFashion & Technology(BUFT) Topic: Reactive Dye Submitted to : MD. RAIJUL ISLAM Lecturer, Dept. of Textile Engineering Submitted By: Shahadat Hossain(171-153-0-155)
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  Content I. Introduction II. Classification III.Chemical Properties IV. Influencing factors V. Fabric Application Based Dyes VI. Trade Name VII. Dyeing mechanism of reactive dye VIII.Fixation & Hydrolysis IX. Application method X. Advantages of the Reactive Dyes XI. Problem & solution of reactive dye XII. Conclusion
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  INTRODUCTION • Fiber reactivedyes are colored organic compounds that are capable of forming a covalent bond between reactive groups of the dye molecule and nucleophilic groups on the polymer chains within the fiber.
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  Why reactive dyeis so called? • Reasons for so named: Reactive dyes are so called because this is the only type of dye, which has reactive group, and that reactive group reacts chemically with fibre polymer molecules and form covalent bond. ... For this reasons the dyes are so called. They are also called 'fibre reactive group'.
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  Classification 1) On thebasis of reactive group: a) Halogen (commonly chlorine) derivatives of nitrogen containing heterocycle, like 3 types- I. Triazine group: procion, cibacron II. Pyridimine group: reactone Quinoxaline III.Quinoxaline dyes:levafix b) Activated vinyl compound: I. Vinyl sulphone:remazol II. Vinyl acrylamide:primazine III.Vinyl sulphonamide: levafix. 2) On the basis of reactivity: I. Lower reactive dye: Here pH is maintained 12-12.5 by using NaOH in bath. II. Medium reactive dye: Here pH is maintained 11-12 by using Na2CO3 in dye bath. III.Higher reactive dye: here pH is maintained 10-11 by using NaHCO3 in dye bath.
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  Classification 3) On thebasis of dyeing temperature: a) Cold brand: These types of dyes contain reactive group of high reactivity. So dyeing can be done in lower temperature i.e. 320-600C. Ex:PROCION M, LIVAFIX E. b) Medium brand: This type of dyes contains reactive groups of moderate reactivity. So dyeing is done in higher temperature than that of cold brand dyes i.e. in between 600-710C temperatures. Example:Remazol, Livafix are medium brand dyes. c) Hot brand: This type of dye contains reactive groups of least reactivity. So high temperature is required for dyeing i.e. 720-930 C temperature is required for dyeing. Example : PRICION H, CIBACRON are hot brand dyes
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  I. Alkali ControllableDye These are of relatively high reactivity and moderate substantively. They are applied at relatively low temperature and level dyeing requires controlled addition of the alkali. Examples include:- DCT, DFCP and VS reactive dyes 2. Salt Controllable Dye These dyes are relatively low reactive towards cotton under allcaline conditions and therefore dyeing temperature will be as high as 80C. Level dyeing requires carefill addition of salt to promote exhaustion. Examples include:- TCP, MCT, and MFT reactive dyes Classification
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  Properties of reactivedye • During the dyeing process, the reactive group of the dye makes covalent bond with the fiber. • These dyes are soluble in water. • These dyes are normally used for dyeing cellulose and protein fibers. • All types of shades are available from these dyes. • The dyeing is done in alkali condition • Wet fastness is well • The brightness and rubbing fastness are comparatively well • The cost of these dyes is cheap • The dyeing process is very easy. • This dye reactive group reacts with –OH groups of cellulose and –NH2 group of proteins fiber.
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  Influencing factors: • Dyeingof cellulosic fiber with reactive dyes is influenced by some factor. Following factors should consider during dyeing operation. 1. pH: Reactive dyeing is done in an alkaline conditon for this reason pH of Me dyeing bath should control. pH should be between 11.5-11. 2.Temperature: Temperature should fix depending on the brand of reactive dyes. 3. Concentration Tolerance : Concentration of electrolyte depends on the type of shade. 4. Time: Dyeing time should be between 60 - 90 minutes. 5. Liquor ratio: Huge amount of water is use during dyeing operation. Higher Me liquor ratio betters the efficiency of dyeing.
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  Fabric Application BasedDyes
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  Trade Name
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  Dyeing mechanism ofreactive dye The dyeing mechanism of material with reactive dye takes place in 3 stages:- I. Exhaustion of dye in presence of electrolyte or (dye absorption). II. Fixation (under the influence of alkali). III. Wash-off (unfixed dye from material surface).
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  Dyeing Mechanism ofReactive Dyes
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  Fixation & Hydrolysis
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  Application method: These are3 application procedures available: 1. Discontinuous method- I. Conventional method II. Exhaust or constant temperature method III. High temperature method IV. Hot critical method. 2. Continuous method- I. Pad dry method II. Pad thermofix method III. Pad-steam method 3. Semi continuous method- I. Pad jig method II. Pad batch method. III. Pad roll method
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  Advantages of theReactive Dyes 1. Permanency of the colour : Fibre Reactive Dyes can be easily said to be the most permanent of all dye types. This is because of an unique quality, unlike other dyes, it can actually form a covalent bond with the substrate (cellulose or protein molecule). After the formation of the bond, there is only one molecule, as the molecule of the is now part of the cellulose fiber molecule. 2. Easy washing : The fibres that are dyed with reactive dyes can be safely dyed even with white garments without the danger of colouring it. 3. Chemical Binding : The chemical bonds as explained above significantly improves the product’s colour stability and washability. Thus, no doubt reactive dyeing of cotton is presently the most popular textile dyeing process in the world.
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  Problem & solutionof reactive dye • Stripping of reactive dye: The reactive dye cannot be satisfactory stripped from fibre due to covalent bond between dye molecule and fibre. Stripping becomes necessary when uneven dyeing occurs.
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  Conclusion Reactive dyeing isone of the important ways of dyeing, but usually in the dyeing process, fabric dyeing liquid through the dip after the need for intermediate drying, which facilitates subsequent steaming or baking fixing to improve processing speed and reduce the time dye hydrolysis, to get high fixation rate and color fastness.
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  Thank You,see youagain  !!