Method of manufacturing a drawn multifilament yarn

Abstract

The invention relates to a method of manufacturing a polyolefin multifilament yarn comprising twisting a partially drawn multifilament yarn and post-twist-drawing the twisted partially drawn multifilament yarn.

1 . A method of manufacturing a multifilament yarn comprising the steps of
 providing a partially drawn multifilament yarn comprising partially drawn filaments,   twisting the partially drawn multifilament yarn to a partially-drawn-twist-level of 4 turns per meter to 600 turns per meter to form a twisted partially drawn multifilament yarn, preferably twisting the partially drawn yarn to a partially-drawn-twist-level of 10 turns per meter to 500 turns per meter, more preferably twisting the partially drawn yarn to a partially-drawn-twist-level of 12 to 200 turns per meter, and   post-twist-drawing the twisted partially drawn multifilament yarn by a draw ratio DR pt  of at least 1.1, preferably post-twist-drawing by DR pt  of at least 1.5, more preferably post-twist-drawing by DR pt  of at least 2, and most preferably post-twist-drawing by DR pt  of at least 3.   
     
     
         2 . Method according to  claim 1 , wherein the partially-drawn-twist-level/DR pt  is between 2-250 turns per meter, preferably the partially-drawn-twist-level/DR pt  is between 2-120 turns per meter. 
     
     
         3 . Method according to  claim 1 , wherein at least one of the filaments of the partially drawn multifilament yarn is selected from the group consisting of (coloured) polyester filaments, HD polyethylene filaments, UHMWPE filaments, polypropylene filaments; preferably the partially drawn multifilament yarn comprises at least 75 number-% UHMWPE filaments; more preferably the partially drawn multifilament yarn comprises at least 90 number-% UHMWPE filaments; and most preferably the filaments of the partially drawn multifilament yarn consist of UHMWPE filaments. 
     
     
         4 . Method according to  claim 1 , wherein twisting of the partially drawn multifilament yarn is realized inline with a drawing step. 
     
     
         5 . Method according to  claim 1 , wherein the steps of twisting the partially drawn multifilament yarn and post-twist-drawing are conducted inline. 
     
     
         6 . Method according to  claim 1 , wherein twisting the partially drawn yarn is conducted by an Uster twister system. 
     
     
         7 . Method according to  claim 1 , wherein twisting the partially drawn yarn is conducted by first winding an untwisted partially drawn multifilament yarn followed by twisting of the partially drawn multifilament yarn by unwinding the partially drawn multifilament yarn using a twisting creel system, preferably the twisting creel system is arranged to conduct the unwinding and twisting inline with the post-twist-drawing process wherein unwinding speed and rotation speed of the twisting creel system is adjusted to the inline post-twist-drawing process. 
     
     
         8 . Method according to  claim 6 , further comprising the step of tensioning the multifilament yarn in a tensioning station after twisting the partially drawn yarn and before post-twist-drawing of the partially drawn yarn. 
     
     
         9 . Method according to  claim 1 , wherein the partially drawn multifilament yarn is post-twist-drawn by a draw ratio DR pt  of at most 100 to form a HPPE multifilament yarn, preferably by a DR pt  of at most 25, and more preferably by a DR pt  of at most 10. 
     
     
         10 . A method of removing a spin solvent from a gelspun multifilament polyolefin yarn comprising the steps of
 providing a multifilament yarn comprising polyolefin filaments and a spin solvent,   twisting the yarn to a twist level of 10 to 600 turns per meter, and   removing at least a part of the spin solvent from the multifilament yarn after twisting the yarn.   
     
     
         11 . Method according to  claim 10 , wherein during the twisting of the multifilament yarn, the spin solvent content of the multifilament yarn is 10 ppm to 1000 ppm based on the weight of polyethylene and spin solvent, preferably the spin solvent content of the multifilament yarn is 20 ppm to 500 ppm based on the weight of polyethylene and spin solvent. 
     
     
         12 . Method according to  claim 10 , wherein during the twisting of the multifilament yarn, the spin solvent content of the multifilament yarn is at least 0.1 wt-% based on the weight of polyethylene and spin solvent, preferably the spin solvent content of the multifilament yarn is at least 0.5 wt-%, more preferably the spin solvent content of the multifilament yarn is at least 2 wt-%, more preferably the spin solvent content of the multifilament yarn is at least 10 wt-%. 
     
     
         13 . Method according to  claim 10 , wherein at least 10 wt-% of the spin solvent present during the twisting is removed after twisting the multifilament yarn, preferably at least 90 wt-% of the spin solvent present during the twisting is removed after twisting the multifilament yarn, most preferably at least 99 wt-% based on solvent content during twisting of the spin solvent present during the twisting is removed after twisting the multifilament yarn. 
     
     
         14 . Method according to  claim 10 , further comprising the step of post-twist-drawing the multifilament yarn by a draw ratio DR pt  of at least 1.1 to form a HPPE multifilament yarn, preferably by a DR pt  of at least 1.5, more preferably by a DR pt  of at least 2, and most preferably by a DR pt  of at least 3. 
     
     
         15 . A method of manufacturing a gelspun HPPE multifilament yarn comprising the steps of
 providing a solution of 3-25 wt-% UHMWPE in a spin solvent (based on UHMWPE and spin solvent in the solution),   spinning the solution through a spinneret having at least two spin holes, quenching the solution in a quench bath to form a solid multifilament yarn comprising partially drawn UHMWPE filaments,   removing of at least a part of the spin solvent from the solid multifilament yarn,   twisting the solid multifilament yarn to a twist level of 10 to 600 turns per meter to form a twisted partially drawn multifilament yarn,   post-twist-drawing the twisted partially drawn multifilament yarn by a draw ratio DR pt  of at least 1.1 to form a HPPE multifilament yarn,   
       wherein twisting, removing of the spin solvent and post-twist-drawing are conducted without adding a spin finish to the multifilament yarn. 
     
     
         16 . Method according to  claim 15  further comprising the step of removing at least 99.5 wt-% of the spin solvent (based on spin solvent in the solution), preferably removing at least 99.9 wt-% of the spin solvent, more preferably removing at least 99.95 wt-% of the spin solvent.