Production processes for manufacturing polyester fibers and yarns, as explained in the following:
Production of ester building unit
In this process a chemical reaction is carried out between monoethylene glycol and dimethyl terephthalate to produce diglycol terephthalate.
In this process (for fiber production) polymerization occurs to diglycol terephtalate to produce polyester polymer.
In this process, molten polyester polymer is pumped to the spinnerettes and the filaments come out to meet a stream of cold air and get solidified. The resulting filament tows collectedin cans feed the next stage. The fineness of the resulting filaments depend on the size of the spinneret holes.
Tensioning and crimping
In this operation, the large number of tows are fed as a layer to a stage of tensioning and crimping, to adjust the fiber fineness and crimp.
Cutting and pressing
The filament sheet is introduced in this stage to a cutting machine which transforms the polyester filaments to fibers with length similar to cotton length or similar to wool length. The resulting fibers are pressed into bales and covered with polyethylene sheets.
In this process (for filament yarn) the number of filaments coming out of the spinneret is much less than in the case of fiber production. The produced yarn in this process is known as “poy” yarn which needs further processing to produce the required yarn
In this stage poy yarn is drawn, twisted and wound to produce polyester filament yarn.
In this process the polyester “poy” (preoriented yarn) is passed in a texturing machine which induce crimp in the filaments, resulting polyester textured yarn.