These are the methods used to obtain fibers with greater volume, greater elasticity and elongation ability, higher strength, greater heat absorption ability, greater moisture absorption ability, air permeability and softer handle by changing the properties of endless synthetic filaments.
It is the process of transforming the tightly and parallelly arranged continuous synthetic filaments into a more open and voluminous structure by applying various chemical, mechanical or thermal processes in order to simulate the natural fiber appearance and handling. textured It called.
What are impacted teeth?
When one or more teeth fails to grow in the correct position and is therefore held below the normal gum line, it is called an impaction. This can be complete, such as completely unerrupted (buried) third molars (wisdom teeth) or partial when just part of the tooth is visible in the mouth.
Why are impactions important?
For best function and appearance the teeth should grow in a healthy alignment. When one or more teeth is impacted, this can affect the function of that tooth but also the function and appearance of other teeth.
Whether all impactions should be treated is still controversial and your dentist and oral and maxillofacial team can explain the advantages and disadvantages or treatment for you, which is usually surgical.
Most of the textile fibers have poor volumetric properties desired by consumers. Almost all of the synthetic filaments have a smooth, shiny, non-hygroscopic, cold structure consisting of parallel fibers like silk. For this reason, techniques used to change the character and volume properties of synthetic fibers are referred to as "texturing” process name is given.
There are 3 basic steps in texturing processes. These are listed below:
2-Giving the texture feature,
3-Fixing the given feature.
The texturing effect is achieved by changing the central stresses created in the yarn cross section not parallel to the yarn axis.
The unsymmetrical tensions that allow the yarn to acquire a crimped structure are obtained in two ways. These are achieved by fixing the form given to the yarn by mechanical, physical and chemical means and by combining two different components of the same polymer with different bending abilities in fiber production. The quality of the textured yarn obtained depends only on the production conditions during the texturing process and the selected texturing method.
3-Chemical thermal method,
After the synthetic yarns are produced, they are not ready for use at the end of the processes. The desired properties are given to the filament yarns by drawing the macromolecules parallel to the yarn axis. It is ensured that the filament yarn is deformed by applying heat treatment, and then the form taken by the yarn is permanent by applying the cooling process. Filament yarns whose molecular positions can be changed by the effect of temperature are called thermoplastics. This feature of filament yarns also forms the basis of the thermomechanical texturing technique. The process steps of the thermomechanical texturing technique are as follows.
The thermo-mechanical method was first applied to synthetic yarns such as acetate and viscose. The method was not used because the fibers were damaged by the effect of heat and their structures were deteriorated. Since the beginning of the 1930s, many thermo-mechanical texturing techniques have been developed besides synthetic yarn production.
These methods are:
1-Torsion (false twist) texturing
5-Knitted disassembly texturing
6-Gear wheel texturing.
Torsion (False Twist) Textured
False twist texturing is one of the most widely used methods today. In this method, the crimping process has become quite economical with false twist spindles rotating at very high speed. In the false twist texturing system, twisting, heat treatment, untwisting and folding are the steps of the process. A yarn, which is conveyed with the help of delivery rollers, passes through the spindle that rotates at 800.000 revolutions per minute. The spindle is hollow, perpendicular to the movement of the thread and is made of very durable material. The part (pin or diabolo) on which the yarn is wound is located between the spindle, the yarn and the receiving roller. The yarn in the stationary state is twisted by the rotation of the yarn on both sides of the spindle. If one side of the spindle is 'S' twisted, the other side is 'Z' twisted.
Air Jet Texturing
The air-jet texturing method is based on the mixing and texturing of filament yarns with the help of compressed air. In the air-jet texturing method, the yarns are sent to the air jet placed between the drafting rollers. In the turbulence region of the air jet, the yarns become crimped by the effect of the compressed air flow. The yarns are coiled by being transferred from the air jet to the bobbin drum with the help of slowly rotating draft rollers.
fluffy filament One of the methods used to obtain yarn is to pass the filaments over the back of a knife. With this method, the yarn is first preheated. The thread is then passed over a cold knife. Meanwhile, the filaments remaining in the inner part of the yarn in contact with the blade are compressed and shortened, the filaments remaining on the outside are stretched by stretching, and the yarn continues to cool as it moves and progresses on the blade. was used. The products produced with the knife texturing method gain a very good two-way elongation feature. Socks with two-way elongation feature a better fit when compared to socks produced with traditional techniques. Knife textured yarns are used in the manufacture of carpets and upholstery fabrics. When the textured yarn with blades is stabilized by heating, the density of the yarn is increased. Thus, the yarns are used in the manufacture of women's clothing, golf clothing and sweaters. Materials such as steel, aluminum and silicon carbide are used to make knives. The radius of the blade should be set between 1960 and 0,0025 mm and should not be too sharp. The blade can be heated either directly or with a contact heater placed on the edge of the blade. Heated blade texturing technique is widely used because it is technically convenient. The temperature of the heaters used varies according to the type of yarn. For example, for polyamide, the temperature should be 0,01 °C. Today, the knife texturing technique is not preferred because the production is at low speeds and the number of filaments in the yarn is limited for the system. Even the fastest machines can produce 173 m in a minute.
In the compression texturing method, a pair of feed rollers take the yarn and feed it into the tube where the yarn is held and deformed, giving it a wrinkled and zigzag appearance. The deformation in the yarn is fixed by the effect of heat. The yarn treated in this way is both more voluminous and softer. The elongation properties are very low compared to the elongation properties of the yarns produced with the false twist texturing technique. The most important feature of this method is that the heat fixation process is done without tension or under very low tensions. The compression texturing method is widely used in carpets, rugs and tufted carpets, in the production of thick number textured filament yarns.
Knitted Stripping Textured
The crimping process is done by the needles of the circular knitting machine. The essence of the method is knitting, fixing and deconstruction of filament yarns. A curved structure is obtained after disassembly. It is done in two ways as discontinuous and continuous heat-fixing method.
1-Discontinuous method: The filament yarns are knitted first in the circular knitting machine. Here, the threads are made into a hose. The braided hose is softly wound onto the reel with the pulley. While it is wrapped on the reel, it is kept at 100-130 ºС with saturated steam for 30-60 minutes. At the end of the process, the hose is cooled and opened. The yarn has the folds of the weave and the breaks are fixed by the effect of its temperature. The removed threads are wound on bobbins. Textured yarns produced by this method:
a-The yarns obtained according to the intermittent method have a wavy structure.
b- He had a soft and pleasant demeanor.
c- The ability to take paint is good.
d- This method can be applied in texturing polyester, polyamide10, 5000polypropylene with 6-6 denier thickness.
e-Upholstery fabric is used for knitting women's socks, laundry, and carpet yarn.
f-Continuous knitting removal method: The continuous knitting removal method is the same as the batch method. Here, the fabric, which is knitted differently, is passed through a hot area (two hot plates) without contacting and fixed before being rolled up. The stability of the curl to be given to the yarns depends on the temperature of the hot zone and the time it passes through the hot zone. Its properties are as in the discrete method. Unlike the continuous knitting removal method, the cost is lower as there is a shortening of the processes. Therefore, it is more economical.
Gear Wheel Texturing
The gear wheel method is also known as the "Crepeset" method. The crimping of the yarns occurs by passing the yarn between the heated gear wheels. This method is generally applied at the end of synthetic yarn production. The purpose here is to pass the hot yarn between the cold gears immediately after the production and to curl the yarn by cooling it.
Threads obtained by the gear wheel method;
1- It is fairly curved.
2- Their volume is not much.
3-The covering ability of the yarns obtained by this method is not good.
It is used for texturing yarns up to 4-1000 denier.
The drawing texturing method has been developed in order to eliminate the costly drawing-bending process and to reduce the cost by performing the drawing and texturing process at the same time. Two methods have been developed for the drawn texturing method.:
1-Separate shooting and texturing (sequental shot texturing)
2-Simultaneous shooting and texturing (simultaneous texturing)
The separate drafting and texturing is called the gradual drafting texturing method, and the simultaneous drafting and texturing is called the stepless drafting texturing method.
After the benefits of the drawn texturing method were seen, textured yarn and machine manufacturers started to work on the drawing texturing methods. Due to the disadvantages of classical texturing methods such as extreme sensitivity to changes in climatic conditions and heat, it was gradually turned to the gradual drawing texturing method. In the drawn texturing method, a drafting element is mounted at the entrance of the texturing machine to ensure that the yarns are drawn at the desired fineness before entering the texturing area. However, due to the high prices of the drawing elements used in this method, the simultaneous drawing texturing method is more preferred.
In this method, the drawing and texturing of the yarns is carried out on machines operating according to the false twist method with two or one heater. The attraction given in the method is provided by a speed difference. In other words, the feed rollers rotate slower than the intermediate rollers in the machine.
In the stepless texturing method, a certain tension occurs during the drawing process. There is a very high tension variation in the heater, especially due to the draft. If the yarn is subjected to excessive mechanical stress in the texturing process, its strength decreases. An important issue in this method is that the yarn is exposed not only to axial pulling forces but also to torsional forces. As a result, the cross-section of the filament yarns in the stepless texturing method is seen as an equilateral triangle. It is not possible to select the exact optimum temperature in the stepless texturing method. As it is known, high temperature is needed in the texturing process. These temperatures are basically slightly below the melting point of the yarn to be texturized. High-temperature spinning can cause excessive crystallization, and the yarn can become quite brittle.
Chemical Thermal Method (Bicomponent Fibers)
Bicomponent fibers are a method discovered due to the curling feature of the wool fiber. The self-forming folds of the wool fiber are due to the different internal structure of the fiber. Bicomponent filament production is based on the principle of passing two different polymers through the same nozzle hole and turning them into a single filament.
For these reasons, bicomponent fibers may show different shortening during the fixation process. In the method, there is no crimping process during the production of the fibers. The crimping process is carried out by heat treatment. By feeding two different polymers into different nozzle holes, fiber structure can be formed with 3 different methods. Side by side, nested and islets in the sea are methods. One of the most preferred methods today is the side-by-side bicomponent filament production method. Two different polymers;
1-Getting different humidity,
2- Different boiling shrinkage,
3- Differences between crystal structures,
4-Different melting temperature
5-Due to the difference in molecular weights, both polymers spontaneously form different folds when subjected to heat treatment. The degree of curl is adjusted by heat treatment.
1- It has less elastic and better form stability than yarns obtained by other texturing methods.
It can be applied for 2-polyamide, polyester, polyacrylnitrile fibers.
Yarns with a thickness of 3-15-1000 denier are produced.
Mechanical Method (Air Texture)
It is the process of mixing and texturing the filament yarns that make up the synthetic yarn with the help of compressed air, and textured yarns are obtained by spraying cold air at high pressure without the effect of heat. In the mechanical method, the yarns are sent to the air jet in the condition of being stuck in the drafting cylinders. The filaments become crimped with the effect of compressed air. The crimped yarn is then taken from the jet with the aid of a drafting roller. It is sent to the drum and coiled.
FALSE TWISTING TEXTURE PRINCIPLE
The first false twist texturing method was a long and tiring process. Today, the old method is not used with modern technology. The following table shows the steps of the old method and the new method.
The yarn received by the delivery rollers is sent into the spindle. The spindle is hollow and there is a pin on which the thread is wound in the direction perpendicular to the thread movement. The pin is between the lead and the receiving cylinder. Rotating the stationary filament yarn spindle will create an equal amount of twist on both sides of the yarn and in opposite directions. “S” twist on one side of the yarn and “Z” twist on the other side. Since the yarn moves, the twist on the yarn after the spindle opens with the effect of twisting in the opposite direction. A twist occurs between the inlet and the spindle, but the yarn becomes untwisted after the region where the twist occurs is passed. For this reason, this method is called the false twist method. The second step in the false twist method is the fixation process. The reason for applying the fixation process is to ensure the permanence of the given twist. With the help of a heater placed between the feeding roller and the spindle, the yarn is heat treated in twisted form. The length of the heater zone is very important for the yarn to reach the desired temperature. The length of the cooling zone is as important as the heating zone. Especially until the heated yarn reaches the twisting unit, the temperature below the glass transition point (70-75 for polyester) °C, 60 for polyamide °C) should fall. Another important point of the heating zone is the optimization of the heat. At very high temperatures, the filaments can stick together. At very low temperatures, a non-permanent curling effect occurs. Both of these conditions affect the bulkiness of the yarn. Another important point is that the thread tension must be constant along the heater thread line. Increasing the tension of the yarn, increasing the speed of the inlet delivery rollers, reduces the tension and ensures that the yarn produced has tighter breaks. After the fixation process, the yarn cools down and the form it takes is fixed.
Usage Areas of Yarns Texturized by False Twist Method
Textured yarns with elastic properties have a wide range of uses.
1- It is used in the manufacture of swimwear, socks, ties, tablecloths, underwear, corsets, gloves, ski suits, medical suits.
2- Due to the high stretching properties of false twist textured yarns, they are used in textile products such as underwear, socks, swimwear, which are combined with their bulkiness feature.
3-Fake twist textured yarns are used in circular knitting at a rate of 80%.
4-Textured filament yarns are widely used in both weft and warp knitting industries.
AIR JET TEXTURING PRINCIPLE
Using compressed air, mixing and texturing the filaments that make up the synthetic yarn structure is called air texturing. In this method, which was used for the first time with the name taslan, the yarn is sent into the jet shown in the figure by means of the drafting cylinder. In the turbulent region of the jet, the filaments encounter the compressed air flow and acquire a coiled structure. The textured yarn is taken from the jet by a drafting cylinder and transferred to the bobbin drum, where it is wound. The most important advantage of this method is that this method can also be applied to non-thermoplastic yarns, since volumizing and gaining elasticity is not done by plastic deformation. Various types of yarns can be obtained by using conveying cylinders rotating at different lengths and varying speeds in air texture. Three different yarn structures can be obtained according to the number of yarns fed into the jet and the feed rate.
1-Single thread texturing process: The yarn from a single bobbin is fed into the jet, making it bulky.
2-Parallel yarn texturing process: The first or more yarns are sent together into the jet.
3-Core and fancy yarn texturing process: Two or more yarns are fed into the jet at different feed rates. While the carrier yarn, which provides the strength of the yarn, is fed 6-8% more, the other yarn or yarns are fed 300% more to obtain fancy yarn.
Features of Air Jet Texturing
1-To be able to blend different yarns
2-To be able to create yarn with a structure and properties similar to spun yarns from natural fibers
3- The feeding yarn used is not limited to synthetic thermoplastic yarns (Polyester, polyamide, polypropylene filament yarns can be used as well as glass fiber viscose, acetate filament yarns.)
4- It was possible to manufacture clothes from the thinnest polyamide and polyester yarns without the need for pre-twisting used in the air-jet texturing method, which was produced in the first years, and to manufacture fabrics to be used in aircraft and space applications by using the thickest glass fiber and carbon.
5- The bulkiness of air-spun yarns does not change in the face of the force that the yarn may encounter during use.
6-The surface of the yarn, which gives a feeling of softness and warmth to the yarn, is covered with fixed piles.
7- It has a better covering property.
8-Since the texturing process does not affect the cross-section of the filament, the woven fabric does not shine in the intense sunlight.
9- Air-jet textured fabrics have higher resistance to abrasion and higher resistance to wrinkles when compared to woolen fabrics.
11-There is less glare and shine on the fabric.
It can be applied to all yarns with 12-40-1250 denier thickness.
13-Due to the use of compressed air, the cost of the process is high.
14- Its characteristic feature is similar to spun yarns in terms of handle, appearance, heating, bulkiness and elasticity.
15- The most important disadvantage of the method is pilling in the tissue during the use of the threads and the hardness of the product.
16-The threads textured according to this method are used in the production of men's clothing fabrics, swimwear, sweaters, carpet upholstery fabric, sewing thread and filter cloth.
Usage Areas of Air-Jet Texturized Yarns
1- Due to the versatility of the yarns of the air-jet texturing process, yarns are preferred in almost every corner of the textile.
4-Tent fabrics, towels, blankets, suitcase fabrics are made of lace.
5-Sheets, curtain fabric, upholstery fabric
6-Sewing thread, filter cloth medical materials, car tire, automobile interior upholstery fabrics, laminated fabrics, insulating material of printed electronic circuits, interlayer fabrics in automobile body.
The filament sections in the textured yarn can be round or can be obtained in different shapes.
Characters gained by the textured yarn
The yarns on which the texturing process is applied gain various properties.
1-More elongation and elasticity
2- Better heat-taking ability
3-A softer and warmer attitude
Properties gained by textile products obtained from textured yarns
1-More elongation and elasticity
2- Good covering
3-A full and soft attitude
4- Form stability and heat retention ability
5-Textured yarns are multi-filament yarns. Textured yarns made of thin filaments have a softer handle. The grip of textured yarns made of thick filaments is harder.
TEXTURED YARN TYPES
Textured yarns can be divided into 3 groups.
1-Elastic textured yarns:
It has high elongation and good recovery properties. Each filament has a two-dimensional, zigzag or three-dimensional helical and twisted form. Elastic texturized yarns can be opened easily under low loads. In particular, zigzag and helical forms can be recovered in the load boat and take their original wavy shape. Since elongation and recovery are important in elastic threads, it is used in clothing that hugs the body. Elastic yarns are produced by thermo-mechanical texturing method.
2-Textured yarns resembling spun yarns from staple fibers (modified):
The filaments that make up the yarns form a tight yarn structure by entangling with each other, leaving spaces where air can enter. For this reason, it does not show elongation in the loads that may occur during production and use. Textured yarns, similar to yarns spun from staple fibers, can be produced by air-jet texturing method and can be used in all areas of textile.
In bulk yarn production, gear wheel, stacking method, knitting removal, air texture method are used. It has a higher volume feature than other yarns. Covering properties are quite good. It is used in the production of woven fabrics whose comfort feature is sought.
During the production of filament yarn, frequent breaks, static electricity and surface abrasions are seen in the filaments during subsequent processes. The most important causes of filaments and yarn breaks are high yarn tension during processing, excessive wear on the surfaces of the yarn that contact the guides, and poor filament cohesion. The oil given to the yarn is defined under names such as spin finish oil, finishing oil, spin finish oil, protection oil. After the production of synthetic fibers, it is applied to the surface of the fiber and covers the surface, giving it an anti-static feature. The properties of the oil applied to the surface of the fiber are determined by considering the material of the fiber and the processes it will see later. If the yarn is to be dyed, the oil is removed by washing the yarn or fabric..
In order to eliminate the problems that occur, oil is given to the yarn before it is wound on the bobbins during the production of the yarn. The cylinder made of ceramic material, which can be applied to the yarn in pure form or in emulsion with water, is half-immersed in the oil trough. The yarn passes tangentially through a moving roller, and the oil on the surface of the roller is transferred to the yarn. The negative aspect of the method is that the oil is not evenly distributed over the entire yarn. In another method, oil is transferred proportionally to the V-shaped ceramic guides into the channel and transferred to the yarn surface. After lubrication, the filament yarns are subjected to heat treatment.
TEXTURED PROPERTIES THAT MUST BE IN THE OIL APPLIED TO THE YARN
1- Anti-oxidant : There should be no color change or bacteria formation after storage on the yarns on which oil is applied; It should not oxidize and cause the formation of insoluble substances. 2-Lubricity : During the processing of the fiber, it should prevent the abrasion of the fiber and reduce the friction between the fiber and the metal and it should have uniform lubricating properties. 3-Cohesion: The applied oil must have a cohesive force that ensures that the oil is balanced and that the filaments adhere to each other. 4-Viscosity stability : The low viscosity of the oil may cause the oil to flow and friction. High viscosity can cause difficulties in lubrication and increase friction. 5- Corrosion resistance : The oil to be used must be resistant to corrosion. During the processing of the filament, rust or corrosion caused by the oil during contact with the metal surfaces forming the machine will cause the machine parts to become unusable after a while, and the rust on the yarn will cause problems in dyeing. 6-Color: The oil used must be transparent. It should not turn yellow during storage. 7-Antistatic control : The oil used must have the feature of preventing the storage of static electricity generated during the processing of the fiber.
Posted by %PM, 11% 709% 2016 18%:%Mar in Yarn Read 13577 times