Twist after dyeing method of processing yarn

#This invention relates to a “twist after dyeing” process by which a process step is eliminated, resulting in a first quality yarn manufactured with less labor and machinery steps. As implied above, the twisting and dyeing steps are reversed from conventional yarn processes. The invention has particular application in the production of sewing thread, although other applications are possible, as well.

#A typical prior art yarn processing method begins with partially-oriented yarn (“POY”), such as polyester. The POY is textured using a false-twist texturing operation, a well-known and widely-used process for imparting desired bulk to the yarn by drawing it and imparting a twist-induced crimp to the yarn. Alternatively, an air-jet texturing process can be used. The false twisted yarn is taken up on a package for further processing. From the false-twist operation the yarn is processed in a twisting operation, usually on a 2-for-1 twister, where actual twist is imparted to the yarn, typically in the range of 1 to 8 turns per inch. The yarn is taken up on the 2-for-1 twister onto a dyeing package. The dyeing packages of yarn are then placed in a dyeing vessel, for example, a pressure kier, and dyed using a combination of water, dye and other chemicals while subjected to heat and pressure for a predetermined period of time sufficient to evenly dye all of the yarn on all of the packages to the proper depth of shade.

#After dyeing the yarn is dried by either subjecting the yarn to heat or extracting the moisture, for example, in a centrifuge or a combination of both. Finally, the yarn is wound off of the dyeing package onto an end use package such as a paper or plastic tube or cone. During this process an appropriate finish such as a lubricant can be applied if required by the anticipated end use. At this point the package is ready for shipment to the customer for use, typically for knitting or weaving fabrics, or for use as sewing thread.

#Some of the objects of the invention have been set forth above. Other objects and advantages of the invention will appear as the description proceeds when taken in conjunction with the following drawings, in which:

#FIG. 1 is a flow diagram of a prior art method of producing yarn wherein the yarn is twisted before dyeing; and

#FIG. 2 is a flow diagram of a method of producing yarn wherein the yarn is dyed before twisting.

#Referring now specifically to the drawings, a prior art method of producing yarn is illustrated in the flow diagram of FIG. 1. The POY 10 is textured using either a false-twist or air-jet texturing operation 11, both well-known and widely-used processes for imparting desired bulk to the yarn 10 by drawing it and imparting a crimp to the yarn 10. The false twisted or air-jet textured yarn 10 is taken up on a package for further processing. From the texturing operation the yarn 10 is processed in a twisting operation 12, usually on a 2-for-1 twister, where actual twist is imparted to the yarn 10, typically in the range of 1 to 8 turns per inch. The yarn 10 is taken up on the 2-for-1 twister onto a dyeing package. The dyeing packages of yarn 10 are then placed in a dyeing vessel, for example, a pressure kier, and dyed in a dyeing process 13 using a combination of water, dye and other chemicals while subjected to heat and pressure for a predetermined period of time sufficient to evenly dye all of the yarn 10 on all of the packages to the proper depth of shade.

#After dyeing the yarn 10 is dried in a drying process 14 by either subjecting the yarn 10 to heat or extracting the moisture, for example, in a centrifuge or a combination of both. Finally, the yarn 10 is wound off of the dyeing package in a winding process 15 onto an end use package such as a paper or plastic tube or cone. During this process an appropriate finish such as a lubricant can be applied if required by the anticipated end use. At this point the package is ready for shipment to the customer for use, typically for knitting or weaving fabrics, or for use as sewing thread.

#Thus three package change steps are required in this prior art method: (1) POY package to the false twist package at process step 11; (2) false-twist package to the dyeing package at process step 12; and (3) dyeing package to the end use package at the final winding process step 15.