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In the polymer plant, basic raw materials for making polyester yarn are terephthalic acid and ethylene glycol. These are stored in silos. From here, they are fed to esterifier where chemical reaction takes place. After the number of hours, the melt is transferred to the polymerizer to complete the reaction. Finally the molten polymer is extruded through the nozzles to form long strands. These are cooled and cut into small pieces, which are called chips. 

These chips could be full dull ,  semi dull ,  bright or cationic . During chemical reaction, certain additives are added to make semi dull or full dull or cationic chips. In case of super bright chips, titanium dio xide or TiO 2 is not added. The addition of TiO makes chips semi dull or full dull. It depends upon the percentage of TiO

During the process of  polymerization, various par ameters are monitored on continuous basis to produce the chips of "A" grade quality. The chips so produced are analyzed for quality like Intrinsic viscosity or I.V., ash content, softening point, moisture after polymerization, yellowness, TiO2 (its nominal value and deviation}, carboxyl or COOH group, DEG content (its nominal value and deviation), pallet dimensions, Color L & B values. 

These are kept in large silos and blended before being transferred to the spinning plant. These chips can be transferred to  the spinning site, either pneumatically or on a small truck. In the first case, yarn spinning unit or partially oriented yarn production facility must be nearby of the chips production site (polymerization plant) so that, material can be transferred using  wider pipes. In the second case, especially when chips manufacturing and POY production facilities are apart at distant places, then only convenient method of transporting chips is using trucks. If chips production facility and POY production facilities are in different countries, then chips bags are only transported by using ships and trucks.  There is alternative method also, but for that polymerization plant and POY production facility must be very close by, so that, instead of making chips, melt can be  transferred directly from the polymerization unit to the spinning unit. This is called  direct spinning. This process saves tremendous amount of money in handling and transportation of the chips and one gets better quality

Process Overview: 

From time to time, different attempts have been made by men to produce artificial fibers. The first attempt was made by Robert Hooke as described in his book Micrographia, whic h was published in 1664. But, Hooke did nothing about it and so far as it is known, he did not make any artificial silk. It was not until the 19th century that real efforts were made. In 1885, Count Hilarie de Chardonnet produced artificial silk from cellulose nitrate. Today, this is of historical interest only, but it was the first artificial silk produced in any considerable quantity and was used extensively at that time. Another attempt was made by Cross & Bevan and in 1891 they discovered the process of  making Viscose Rayon  from cellulose. In 1921, Dr. Henery Dreyfus succeeded in finding a way of converting the soluble acetate into an artificial silk and this is the origin of term "Rayon" (now used as a general term for all regenerated fibers made from c ellulose origins). For next few years, no new fibers were produced though several improvements were made in the process of making viscose fiber. 

 

Development of Spinning process: 

History of the development of Polyester Fibers: 

 

The work of Carothers between 1928-1932 laid the foundation for all processes used in the production of polyester, polymaide using polycondensation process. Bischoff, Fischer and Staudinger were concerned with similar problems without economic sucess. However Carothers was the first to  produce spinnable polyester of high molecular weight. Carothers and his coworker Hill, jointly suceeded in carrying out the polycondensation as part of a molecular distillation or simply by passing nitrogen through the condensation melt until a fiber- forming polyester resulted. The polycondensation of ethylene glycol and sebacic acid produced a melt from which filaments can be drawn by contact with a glass rod; when these solidified they could be strtched upto four times their original length. Carothers called this process cold drawing and it made filaments resistant to breaking and bending. Carothers and Hill also produced other fiber making polyesters. Carothers and his team also turned their attention to polyamides in order to exploit the discovery comme rcially because softening or melting points of the polyesters produced from aliphatic dicarboxylic acids and glycols are considerably lower than those of the corresponding polyamides. In this respect the polyamide "66"which Carothers produced in 1931 from hexamethylenediamine and adipic acid proved to be eminently suitable; it was the so called "nylon". The differences in melting points and, therefore, thermal stability, e.g. resistance to pressing, 

between polyesters and the corresponding polyamides is very large. 

Other institutes and research organizations took up the work which Carothers and his team started so very successfully on fiber formation from polyester and polyamide compunds and these were extended in other directions. Particular attention was pai d to the replacement of dicarboxylic acids, diamines, diols or aminocarboxylic acids used by Carothers with chemical substances of the type that can be produced economically and will lead to polymeric compounds capable of conversion into high quality textile products. In the course of this work Schlack in 1938 succeeded in developing a process permitting the use of caprolactam (the lactam of 6 -aminohexanoic acid which can be produced cheaply and is readily puified for making polyamides; this is the process that has found global application particularly as a continuous process in large scale production.  

In order to give the fibers resulting from polycondensation products a greater thermal stability and higher melting 

points, Schlack and Ludewig in 1939 used terephthalic acid to produce polyamides ("Wetrelon"). Simultaneously, other aromatic di - carboxylic acids were tested, e.g. by Hubert and Ludewig using naphthalenedicarboxylic acid instead of the aliphatic dicarboxylic acids for the condensation, which gave  polyamides. 

In the early 1940s, the use of terephthalic acid for development of polyester fibers was implemented almost at the same time in Germany by Schlack at a branch of Agfa Wolfen and by Whinfield & Dickson in England in the laboratories of the Calico Printers Association. Whinfield and Dickson preferred using a combination of terephthalic acid and ethylene glycol to produce polyester. Schlack used terephthalic acid and 1,4 butanediol. Both polyesters are crystalline and well suited for forming fibe rs. The melting points of different polyesters depends upon the number of CH2 groups in the diol. The combination chosen by Whinfield and Dickson was the most favorable from the point of economy and application to textile usage and that is the reason it ha s succeeded over the combination used by Schlack.Mass production based the technological development of polyester fibers originated by Whinfield and Dickson was carried out from 1947 in United Kingdom by I.C.I. and in USA by Dupont after both companies ac quired the patent rights from Calico Printers' Association Ltd. in Manchester. The I.C.I. marketed their polyester fiber as 'Terylene' while Dupont marketed their product as 'Dacron'. After this patent rights were make available to many other firms in vari ous other countries.  

All the procedures have one thing in common: 

a.   Preparation of the polymers;   

b.   Spinning of the polymers into filaments; and  

c.   Further processing of filaments into continuous filament or staple fibers.    

This seperation of the production into  three separate steps is generally found in many plants. However there is an 

increasing tendency to merge two of these steps, for instance by continuous manufacturer of polymers and spinning the condensation melt in one stage, or by merging the spinning pr ocess with a drawing process into the so - called "spin drawing". The manufacturer of polyester filaments, e.g. tow, is also feasible in a one- step process, i.e. polycondensation; spinning and drawing is here combined into one single process to obtain high tenacity filaments. Most man made fibers are produced either in the form of continuous filament or in the form of cut staple. Fabrics made from the former suffer lack of cover, feel & warmth; while fabrics made from the latter lack resistance to pilling. 

Actual Spinning Process (Historical Development):  

The formation of molten polymer into filaments, called the spinning process, generally consisting of following steps:  

1.   Manufacturer of the spinning melt    

2.   Spinning of the melt    

3.   Fiber formation below the spinne rete   

4.   Preparation and winding on of the spun filaments    

Chips made at polymerization stage were conveyed to the spinning plant using various systems like: trucks, 

pneumatically conveying systems etc. These were conveyed to a small hopper just above the mel ting device (extruder). From here the molten polymer was forced to spinnerets via spinning pumps. It was leaving the spinnerte orifice in the form of liquid thread which was solidifying after extrusion using cold air. After application of the finish or lub rication it was wound on the bobbins for further processing. Earlier, speed of about 800 m/min was possible and yarn produced was known as Un Drawn Yarn or UDY having a shelf life of only 2 -3 days. Then MOY or Medium Oriented Yarn came into picture which w as spun at the stake up speed of 2200 -2400 m/min. This has little better shelf life. After that POY or Partially Orinted Yarn came into picture. It has much better shelf life, better processing, much more uniform dyeing. POY speed was generally between 3000 -3400 m/min. It is to be noted here that "POY" is itself a complete word which means "partially oriented yarn". However, to furtherclarify this, we had to choose the name "POY Yarn.com". Now a days HOY or Highly Oriented Yarn, FDY or Fully Drawn Yarns are possible at the speed ranging from 6000 m/min  or above. For full process,Please enter to www.jwellpoly.com  www.jwellpoly.cn for more details  .  

 

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