Fiber dyeing is used in the production of melange yarn and for carpet yarns..
Fiber dyeing is the process of dyeing textile fibers in mass form without any physical treatment.Fiber dyeing is more common in wool, polyamide and acrylic fibers.When the cotton material gets wet, it swells and gains a tighter structure, making it difficult for the dye liquor to circulate in the mass.Therefore, such an application is not preferred.However, errors in fiber dyeing or uneven dyeing can be easily corrected during blowroom.
ADVANTAGES OF FIBER DYEING
In fiber dyeing, the dyestuff penetrates perfectly into the fibers and good color uniformity is achieved.
This method is the easiest dyeing method. Rubbing fastness is high.
DISADVANTAGES OF FIBER DYEING
1-It poses a great risk in fashion. Because the color of the fabric should be decided months in advance.
2- Raw or white yarn is preferred for yarn production. Because when two different colors will be worked one after the other, the remnants of the previous one should be completely cleaned from the machine.
3-Dyed fibers lose some of their flexibility. This creates difficulties during spinning.
FIBER DYEING MACHINES
In a dyeing machine, the main compartment where the dye solution is placed and dyeing is made consists of the side compartment where the additions are made, the loading and unloading system, the heater and the control mechanisms.The metal used for dyeing machines should be stainless steel.Otherwise, corrosive chemicals (acid, base, etc.) put into it cause corrosion (abrasion).Therefore, machinery and equipment must be made of a material that will not be affected by acids and bases.The concentrated dyestuff solution should be diluted with the bath solution before it comes into direct contact with the material to be dyed. It contains an additional tank located on the side of the machine.In this section, the chemicals to be put into the liquor are prepared here and added slowly into the bath.
FIBER DYEING PROCESS
continuousTwo types of fiber dyeing systems, ü and apparatus vardır.
Painting in apparatus is the most widely used method today.
In continuous dyeing machines, there are two systems in which the fiber can be dyed continuously.
In the first system, open fiber travels in the liquor and goes through spinning, water spraying and drying processes in order.
In the second system, an equal amount of fiber is conveyed to two dyeing vats via a conveyor belt.
Thanks to the suction made through the drum in the first dyeing vessel, the dyestuff penetrates into the fiber and is conveyed to the conveyor belt. The same process is repeated in the second boat.Drying with suction drum dryers is applied at the exit.The dyeing process in the apparatus is based on placing the fibers in bulk in large tanks containing dyebath and circulating the liquor through this heap at the required temperatures.In the apparatus, the liquor is mobile, the material is immobile.In order to feed the fiber to the machine in mass, it is necessary to press it in the press machines.For this process, the fiber is pressed in perforated cages with 80-90°C hot water.During the pressing process, wetting is done to prevent the fiber from swelling and jamming when it encounters the dye bath and making it difficult to get dye in between. The pre-wetted fiber is wet-compacted so that dye uptake is more comfortable. These compressed fiber masses are called cakes. Three cakes are fed into one machine. Each of the cakes varies between 500-600 kg. This machine is used in fiber dyeing process.Fiber dyeing is done in pressurized cylindrical dyeing boilers.The upper part of the machine is the cover and has a dome-like structure.This cover is tightened to the machine with screws so that the cover does not open when the inside of the machine is pressurized.In the main part (body) of the machine, there is a cage with a diameter of 150 cm and a depth of 80 cm, where the fiber can be placed in bulk. The middle of the cylindrical cage is empty and when the cage is placed in the machine, a perforated pipe in the middle of the machine passes through this gap.It is placed in the fiber cage by compressing it with water so that its density is 300-480 g/L.Folt circulation can be adjusted from outside to inside and inside to outside of the cage with the help of a valve or automatically.During this process, the dye solution should penetrate all parts of the material evenly.But this movement should not be too violent. Otherwise, the material may be damaged.At the base of the machine, there are heat exchangers placed helically, under the cage.In this way, the dyestuff inside the machine can be heated.These heaters are designed to ensure that all sides of the liquor are at the same temperature.
Fiber dyeing is done by using the extrusion method in pressure boilers that can reach high temperatures.The liquor ratio varies between 1:8-1:10.It is also used for dyeing tops and bobbins when the fiber basket placed in the tubs used for fiber dyeing is changed.
AFTER TRANSACTIONS
After the finished material has gone through all the fixation process specific to the dyestuff used, it is subjected to a drying process to remove excess water.This drying process is primarily a process of removing surface water with a spin.Surface water is squeezed in centrifugal machines operating at high speeds with the principle of centrifugal force.The dyed fiber cake is removed from the machine and fed into the tub of the centrifuge machine and squeezing takes place.Heat transfer drying devices are used to remove capillary (inter-fiber) water.Drying of fibers and tops takes place in blow dryers with hot air passing through endless belts.After the drying process is finished, the fiber in bales is compressed and made ready for shipment.Fiber dyeing is preferred because of the high penetration and fastness of the dye.
lessontextile 
