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SEMI CONTINUOUS DYEING PROCESS
In the process of semi-continuous dyeing that consists of pad-batch, pad-jig, pad-roll the fabric is first impregnated with the dye-liquor in, what is called a padding machine. Then it is subjected to batch wise treatment in a jigger. It could also be stored with a slow rotation for many hours. In the pad-batch this treatment is done at room temperature while in pad-roll it is done at increased temperature by employing a heating chamber. This helps in fixation of the dyes on to the fibre. After this fixation process, the material in full width is thoroughly cleansed and rinsed in continuous washing machines. There is only one point of difference between Continuous and semi-continuous dyeing process is that in semi-continuous dyeing, the dye is applied continuously by a padding. The fixation and washing remaining discontinuous. Liquor Ratio in semi-continuous dyeing is not of much importance and is not taken as a parameter. One of the widely used techniques for semi-continuous dyeing process is the Pad Batch Dyeing a schematic diagram is given here for the semi-continuous dyeing process.
PAD BATCH DYEING
Pad Batch Dyeing is one of the widely used technique for semi-continuous dyeing process. It is mainly used in the dyeing of cellulosic fibre like cotton or viscose (knit and woven fabric) with reactive dyes. Pad batch dyeing is a textile dyeing process that offers some unique advantages in the form of versatility, simplicity, and flexibility and a substantial reduction in capital investment for equipment. It is primarily a cold method that is the reason why it is sometimes referred to as the cold pad batch dyeing.
Working of a Cold Pad Dyeing Process
The technique or process used in pad-batch dyeing starts with saturating first the prepared fabric with pre-mixed dye liquor. Then it is passed through rollers. The rollers, or padders, effectively forces the dyestuff into the fabric. In the process, excess dye solution is also removed. After removal of excess dye stuff the fabric is subsequently "batched". This batching is done by either storing it in rolls or in boxes. It takes a minimum of 4-12 hours. The batches are generally enclosed by plastic films. This prevents absorption of carbon dioxide and water evaporation. Finally as the reaction is complete the fabrics are washed. This is done by becks, beams, or any other washing devices.
Special Features of Pad Batch Dyeing Process
Significant cost and waste reduction as compared to other conventional dyeing processes.
Total elimination of the need for salt and other specialty chemicals. For example there is no need for anti-migrants, leveling agents and fixatives that are necessary in conventional dyebaths.
Optimum utilisation of dyes that eliminates specialty chemicals, cuts down chemical costs and waste loads in the effluent. All this results in a formidable reduction in wastewater treatment costs.
Excellent wet fastness properties.
Pad batch dyeing cuts energy and water consumption owing to low bath ratio (dye:water) required for the process. This is because unlike other dyeing processes it does not function at high temperatures.
A uniform dye quality is achieved with even color absorbency and colour fastness.
As compared to rope dyeing, Pad batch dyeing produces much lower defect levels.
In pad batch dyeing, qualities like high shade reliability and repeatability are common. This is because of high reactivity dyes with rapid fixation rate and stability.
Lastly Pad batch dyeing can also improve product quality. The fabric undergoing the cold pad batch dyeing process is able to retain an uniformly coloured appearance. It shows added luster and gives a gentle feel. The fabric gives a brighter look in shades.
Total elimination of the need for salt and other specialty chemicals. For example there is no need for anti-migrants, leveling agents and fixatives that are necessary in conventional dyebaths.
Optimum utilisation of dyes that eliminates specialty chemicals, cuts down chemical costs and waste loads in the effluent. All this results in a formidable reduction in wastewater treatment costs.
Excellent wet fastness properties.
Pad batch dyeing cuts energy and water consumption owing to low bath ratio (dye:water) required for the process. This is because unlike other dyeing processes it does not function at high temperatures.
A uniform dye quality is achieved with even color absorbency and colour fastness.
As compared to rope dyeing, Pad batch dyeing produces much lower defect levels.
In pad batch dyeing, qualities like high shade reliability and repeatability are common. This is because of high reactivity dyes with rapid fixation rate and stability.
Lastly Pad batch dyeing can also improve product quality. The fabric undergoing the cold pad batch dyeing process is able to retain an uniformly coloured appearance. It shows added luster and gives a gentle feel. The fabric gives a brighter look in shades.
BATCH DYEING PROCESS
Batch Dyeing Process is the most popular and common method used for dyeing of textile materials. Batch dyeing is also sometimes referred to as Exhaust dyeing. This is because in this process, the dye gets slowly transferred from a comparatively large volume dyebath to the substrate or material that is to be dyed. The time taken is also longer. The dye is meant to 'exhaust' from dyebath to the substrate. In batch processes, textile substrates can be easily dyed at any stage of their assembly into the desired textile product. This includes fiber, yarn, fabric or garment. Some type of batch dyeing machines can function at temperatures only up to 1000oC. For example cotton, rayon, nylon, wool etc. can be dyed at 1000oC or lower temperatures. While polyester and some other synthetic fibers are dyed at 1000 Centigrade or even higher temperatures. There are three general types of batch dyeing machines. The first type is the one where there is circulation of fabric. Second type is the one where the dyebath gets circulated while the material that is being dyed remains stationary, and finally the third type where both the bath and material to be dyed gets circulated. Examples of dyeing machines that utilizes batch dyeing process are Beck, Jet, Jigs, Beam Package dyeing machines etc.
THERMOSOL DYEING PROCESS
The working of a continuous dyeing process is described here. The textile substrates are feeded continuously into a dye range. The speeds can vary between 50 to 250 meters per minute. According to Industry estimates Continuous dyeing is a popular dyeing method and accounts for around 60% of total yardage of the products that are dyed. A Continuous dyeing process typically consists the following. Dye application, dye fixation with heat or chemicals and finally washing. Continuous dyeing has been found to be most suitable for woven fabrics. Mostly continuous dye ranges are designed for dyeing blends of polyester and cotton. The step of padding plays a key role in the operation of continuous dyeing. Sometimes Nylon carpets are also dyed in continuous processes, but the design ranges for them is unlike that for flat fabrics. Warps are also dyed in continuous process. Very good examples of such warp dyeing are long chain warp dyeing and slasher dyeing using indigo.A continuous dye range has been found useful and economically sustainable for dyeing long runs of a given shade. One important factor that separates continuous dyeing from batch dyeing is the tolerance factor for color variation. That is more for continuous dyeing as compared to batch dyeing. This is so because of two reasons a) the speed of the process. b) presence of a large number of process variables which affects dye application. The process that is illustrated below is designed for dyeing of blended fabric of polyester and cotton.
Process for continuous thermosol dyeing of textile fabrics
A textile fabric formed of synthetic fibrous material or blends with natural fibers to which dyestuffs have been applied is subjected to a thermosol heat treatment by directing the fabric supported on an air permeable conveyor through a heated oven while directing heated air downwardly through the fabric and through the underlying supporting conveyor and while at predetermined longitudinally spaced locations as the fabric travels through the oven directing heated air upwardly through the open mesh conveyor and into contact with the fabric so as to lift portions of the fabric from the conveyor to permit free shrinkage and bulking of the fabric while avoiding distortion of the fabric or obtaining an undesirable ironed surface appearance as would occur if the fabric were pinned to the conveyor. This method also achieves very rapid and efficient heat transfer to the fabric and thus avoids the extreme time and temperature conditions which result in harsh treatment of the fabric.
DETAILS OF JIG DYEING MACHINE
A Jig Dyeing machine, is an efficient dyeing technique. It is also known by the name of jigger. Jig Dyeing machine processes fabrics in open width to avoid creasing problems in fabric dyeing. The process works like this. The Jig Dyeing machine operates by transferring the fabric back and forth. This happens from roller to roller via the medium of a dyebath, that is located at the base of the machine. As soon as the second roller gets full, the direction of movement of fabric can be reversed. In Jig dyeing, the duration of the process is measured on the basis of the number of passages or ends of the fabric passing through the dye bath from roller to roller. The end in dyeing parlance is known as the passing of fabric through a dye liquor from one roller to the other one.
INTRODUCTION
A jigger is composed of a trapezoidal tub containing the bath and two rolls on which the fabric is alternatively wound. In this type of machine the bath is stationary while the fabric is in motion. The fabric, initially wound on the first roll, flows through the bath and then is wound on the other one; the rotation is then reversed and the cycle continues. The fabric is led in its path by a few small guide rollers.
HT jiggers are also produced, allowing treatments at temperatures above 100 °C. This type of machine is used not only for dyeing, but also for various wet treatments on fabrics in full width.
The main disadvantage of this system is the risk of non-homogeneity between the initial and final part of the roll. This is due to variations in feed speed and tension of the fabric, or temperature and chemicals concentration in the bath during the period of the treatment. However, in modern jiggers tension of the fabric is kept constant during the whole process, thanks to special devices.
HT jiggers are also produced, allowing treatments at temperatures above 100 °C. This type of machine is used not only for dyeing, but also for various wet treatments on fabrics in full width.
The main disadvantage of this system is the risk of non-homogeneity between the initial and final part of the roll. This is due to variations in feed speed and tension of the fabric, or temperature and chemicals concentration in the bath during the period of the treatment. However, in modern jiggers tension of the fabric is kept constant during the whole process, thanks to special devices.
JIG MASTER
CONSTANT FABRIC TENSION AND SPEED DUE TO FREQUENCY CONTROLLED ELECTRIC DRIVES.
(2) SELF-CLEANING FILTER STATION
(3) FREQUENCY CONTROLLED BATCHING ROLLS WITH DIGITAL SPEED INDICATION.
(4) FAST AND TENSIONLESS UNLOADING
(5) TWO STAINLESS STEEL CIRCULATION PUMPS WITH MECHANICAL SEAL.
(6) EXTRA WIDE WINDOWS
(7) THREE CONVEX GUIDE ROLLERS
(8) BALANCED EXPANDERS FOR CREASE-FREE WINDING.
(9) HIGH CAPACITY HEAT EXCHANGER.
(10) FULLY AUTOMATIC ADD TANK
(11) DOSING PUMP.
(12) TWO BATH EXECUTION OF THE VAT FOR REDUCTION OF THE RINSE WATER.
AUTOMATIC JIG
SUITABLE FOR WOVEN/KNIT FABRIC
(2) USEFUL FABRIC WIDTH : 1200MM – 3200MM
(3) FABRIC SPEED ADJUSTABLE FROM 11 TO 110 MTRS/MIN
(4) FABRIC TENSION ADJUSTABLE FROM 10 TO 60 KGS,
(5) THE TROUGH IS BUILT IN STAINLESS STEEL
(6) LIQUOR RATIO 1:2.
(7) DOORS WITH GLASS WINDOWS ARE PNEUMATICALLY LIFTED.
(8) FABRIC TAKE OFF THROUGH WINCH
(9) INDIRECT HEATING THROUGH EXTERNAL HEAT EXCHANGER.
(10) DYE LIQUOR CIRCULATION IS THROUGH PUMP.
(11) TO PREVENT DRIPPING OF CONDENSATE, HEATING COILS ABOVE HOOD
(12) AUTOMATIC ROCKING DEVICE
(13) TO AVOID UNBALANCING OF BATCHES WHILE MACHINE IS STOPPED.
(14) DYE LIQUOR FILTER OUTSIDE THE MACHINE WITH LARGE FILTERING SURFACE
(15) ADDITIONAL DOSING TANK WITH PUMP FOR DYEING.
High Temperature Jig
(1)IT CAN BE CONFIGURED FOR THE DYEING PROCESS WITH USE OF VAT-TYPE DYES.
(2)DYEING UNDER PRESSURIZED CONDITIONS
(3)WHICH ELIMINATES THE NEED FOR CHEMICAL CARRIERS
(4)REDUCES THE TIME OF DYE CYCLES FOR MOST FABRICS.
(5)THUS IT IS ENVIRONMENTALLY FRIENDLY.
Atmospheric Jig
MOSTLY USED TO PROCESS NATURAL AND REGENERATED FIBERS
(2) AUTOMATED DOSING SYSTEM ADDITION TANKS
(3) ENCLOSED COIL FOR HEATING.
(4) A CIRCULATION AND DOSING PUMP SYSTEM
(5) FEEDS DYES AND CHEMICALS INTO DYE BATH ACCORDING TO THE RECIPE LOADED BY OPERATOR.
Jumbo Jigger Machine
(1)SEMI AUTO JIGGER M/C
(2)RUN FABRIC WITH LEAST TENSION ACHIEVING BY MEANS OF SPECIALLY DESIGNED BRAKES AND DIFFERENTIAL GEARING UNIT
(3)IT HAS HEAVY DUTY DRAW ROLLER AND DIFFERENTIAL GEARBOX
(4)CREASELESS CLOTH FEEDING SYSTEM
(5)BY MEANS OF FLOATING DEVICE WITH TURN-BACKLE ARRANGEMENT
(6) AUTO REVERSIBLE STARTERS ARE ALSO PROVIDED.
Super Jumbo Jigger S J 1000
(1)EQUIPMENT FOR OPEN WIDTH SCOURING & BLEACHING OF FABRIC IN BATCH FORM.
(2)REQUIRES LESS SPACE, WATER, CHEMICALS AND MAN POWER
(3)MACHINES ARE AVAILABLE FROM 1500 MM TO 3400 MM FABRIC WIDTH.
(4)HEAVY DUTY CAST IRON STRUCTURE
(5)SQUEEZE THE FABRIC BY PNEUMATIC PRESSURE ARRANGEMENT.
Hydraulic Type Jumbo Jigger Machine
(1)SLOW START/STOP.
(2) TROUGH IS ENTIRELY BUILT IN STAINLESS STEEL
(3) THE DOOR OF MACHINE PNEUMATICALLY LIFTED & LOWERED.
(4) THE DOORS AND WINDOWS ARE SEALED WITH SPECIAL GASKET AGAINST STEAM ESCAPE.
(5) TO PREVENT DRIPPING OF CONDENSATE THERE ARE STEAM COILS IN THE HOOD.
(6) SERVICE TANK FOR DYE STUFFS & CHEMICALS.
(7) DYE LIQUOR CIRCULATION BY MEANS OF PUMP
(8) DYE LIQUOR FILTER OUT SIDE THE MACHINE WITH LARGE FILTERING SURFACE.
(9) USED FOR BETTER LEVELED DYEING OR SWITCHING THE FLOW ON THE SPRAY PIPES FOR MORE EFFICIENT WASHING OR RAISING.
(10) FULLY AUTOMATIC
TYPES OF JIGGER MACHINE
Hydraulic Type Jumbo Jigger Machine
Super Jumbo Jigger S J 1000
Atmospheric Jig
High Temperature Jig
Automatic Jigger
Super Jumbo Jigger S J 1000
Atmospheric Jig
High Temperature Jig
Automatic Jigger
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