Tuesday, 28 April 2015

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Reactive Dye

Reactive Dye

Reactive Dye
Reactive Dye
Reactive dyes are dyes which normally have the basic structure of acid, direct , or mordant dyes yet which moreover have a reactive group equipped for covalent bond formation with the fiber. Since the fiber must have sensible reactivity toward the dye reactive group, application of these dyes has been constrained to cellulosic , protein, and nylon fibers for the most part.

The fastness of reactive dyes covalently bound to the fiber is brilliant. Reactive practical groups have been chosen for fuse into reactive dyes which will respond promptly with the fiber after diffusion into the structure yet which won't hydrolyze (decompose) in the water dissolvable utilized as a part of dye application. Acidic or basic conditions are fundamental for successful and quick response of the reactive dye with the fiber, so dye application is completed at either somewhat acid or basic pH (hydrogen particle focus). Procion dyes are the best known of the reactive dyes.

Properties of reactive dye

>> Reactive Dyes are anionic dyes, which are utilized for dyeing cellulose, protein and polyamide filaments.

>> Reactive Dyes are found in force, fluid and print glue structure.

>> Amid dyeing the reactive gathering of this dye frames covalent bond with fiber polymer and turns into an indispensable parts of the fiber.

>> Reactive dyes are dissolvable in water.

>> They have great light speed with rating around 6. The dyes have exceptionally stable electron plan and can secure the corrupting impact of ultra-violet beam.

>> Material materials dyed with reactive dyes have great wash quickness with rating reactive dye gives brighter shades and has moderate rubbing speed.

>> Dyeing technique for reactive dyes is simple. It obliges less time and low temperature for dyeing.

>> Reactive dyes are nearly shabby

>> Reactive dyes have great sweat quickness with rating 4-5.

>> Reactive dyes have great sweat quickness.

Characterization of reactive dyes:

Reactive dyes may be characterized in different routes as underneath:

1) On the premise of reactive gathering: 
a) Halogen (normally chlorine) subordinates of nitrogen containing heterocycle, similar to 3 sorts

Triazine bunch
Pyridimine bunch
Quinoxaline dyes


Triazine subsidiaries: procion, cibacron.
Pyridimine subsidiaries: reactone
Quinoxaline subsidiaries: levafix.

b) Actuated vinyl compound: 

Vinyl sulphone
Vinyl acrylamide
Vinyl sulphonamide.


Vinyl sulphone: remazol
Vinyl acrylamide: primazine
Vinyl sulphonamide: levafix.

2) On the premise of reactivity:
a) Lower reactive dye: Medium reactive dye: here pH is kept up 11-12 by utilizing Na2CO3 as a part of dye shower.
b) Higher reactive dye: here pH is kept up 10-11 by utilizing NaHCO3 as a part of dye shower.

3) On the premise of dyeing temperature:

a) Chilly brand: 
These sorts of dyes contain reactive gathering of high reactivity. So dyeing could be possible in lower temperature i.e. 320-600C.

b) Medium brand:
This sort of dyes contains reactive gatherings of moderate reactivity. So dyeing is done in higher temperature than that of cool brand dyes i.e. in the middle of 600-710C temperatures.

c) Hot brand: 
This sort of dye contains reactive gatherings of minimum reactivity. So high temperature is needed for dyeing i.e. 720-930 C temperature is needed for dyeing.

Dyeing instrument of reactive dye:
The dyeing instrument of material with reactive dye happens in 3 stages:-
Depletion of dye in vicinity of electrolyte or dye retention.
Obsession affected by soluble base.
wash-off the unfixed dye from material surface.
Presently they are said beneath:

Dye assimilation: 
At the point when fiber is submerged in dye alcohol, an electrolyte is added to help the depletion of dye. Here NaCl is utilized as the electrolyte. This electrolyte kill assimilation. So when the material is acquaints with dye alcohol the dye is depleted on to the fiber.

Obsession of dye means the response of reactive gathering of dye with terminal –OH or-NH2 gathering of fiber and subsequently shaping solid covalent bond with the fiber and consequently framing solid covalent bond with the fiber. This is a critical stage, which is controlled by keeping up fitting pH by including antacid. The salt utilized for this make fitting pH in dye shower and do as the dye-settling specialists.

3. Wash-off: 
As the dyeing is finished, a great wash must be connected to the material to expel additional and unfixed dyes from material surface. This is fundamental for level dyeing and great wash-speed. It is finished by a progression of hot wash, chilly wash and cleanser arrangement wash.

Application development

These are 3 application strategies accessible: 

1. Intermittent technique
Routine technique
Fumes or steady temperature technique
High temperature system
Hot basic technique.

2. Cotinuous system
Cushion steam system
Cushion dry system
Cushion thermofix system

3. Semi persistent technique
Cushion roll system
Cushion jig system
Cushion group strategy.

Stripping of Reactive Dye

The reactive dye can't be attractive stripped from fiber because of covalent bond between dye particle and fiber. Stripping gets to be essential when uneven dyeing happens.

Halfway stripping of Reactive Dye

Halfway stripping is gotten by treating the dyed fabric with weaken acidic corrosive or formic corrosive. Here temperature is raised to 70-100°C and treatment is proceeded until shade is result of hydrolysis. The measure of corrosive utilized is as beneath: -

Frigid acidic corrosive : 5-10 sections
With water :1000 sections
On the other hand
Formic corrosive :2.5 to 10 sections
With water :1000 sections
Temperature : 70 - 100°C
Time : until coveted shade is gotten.

Distinctive strategies for reactive dye application: 
1) Cushion group strategy.
Cushion group methodologies are of two sorts

a) Cushion (antacid)-cluster (frosty) process.
b) Cushion (antacid)-cluster (warm or hot) process.

2) Cushion dry technique

3) Cushion steam technique


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