Process for removing residual spin solvent from a gel spun filament, the filament, multi-filament yarn and products comprising the filament

Abstract

Processes for removing residual spin solvent from a gel spun, UHMwPE filament having an effective diameter of above 16 μm, comprise the steps of removing residual spin solvent from the filament to a level of below 100 ppm at elevated temperature, while keeping the filament taut. Gel spun UHMwPE filaments having an effective diameter of above 16 μm and a residual spin solvent residue of less than 100 ppm are also provided. Preferably the filament has a creep rate, measured at 50° C., under a load, so that the initial stress is 600 MPa, of less than 5·10 −6 sec −1 .

1 . A process for removing residual spin solvent from a gel spun, UHMwPE filament, comprising the steps of:
 (a) providing a gel spun UHMwPE filament having a titer of 2-100 dtex, and a residual spin solvent content of between 100 and 2000 ppm,   (b) winding the filament provided in step a) around a frame such that the filament is kept taut with a tension of above 0.15 g/dtex, and   (c) removing residual spin solvent from the filament by subjecting the filament around a frame of step b) to an elevated temperature above 80° C. and below 140° C., to obtain a treated UHMwPE filament having a residual solvent level of below 60 ppm.   
     
     
         2 . The process according to  claim 1 , wherein the filament provided in step a) has residual spin solvent content of more than 200 ppm. 
     
     
         3 . The process according to  claim 1 , wherein the filament provided in step a) has a titer of 2-30 dtex. 
     
     
         4 . The process according to  claim 1 , wherein the filament is provided in step a) as a multi-filament yarn. 
     
     
         5 . The process according to  claim 1 , wherein the elevated temperature is above 90° C. 
     
     
         6 . The process according to  claim 1 , wherein the elevated temperature is above 100° C. 
     
     
         7 . The process according to  claim 1 , wherein the elevated temperature is below 130° C. 
     
     
         8 . The process according to  claim 1 , wherein the elevated temperature is below 125° C. 
     
     
         9 . The process according to  claim 1 , wherein step (c) is carried out in an environment having an oxygen content of less than 3 mol/m 3 . 
     
     
         10 . The process according to  claim 9 , wherein step (c) is carried out under a reduced air pressure. 
     
     
         11 . The process according to  claim 1 , wherein step (c) is carried out for at least half an hour. 
     
     
         12 . The process according to  claim 1 , wherein the treated filament obtained in step (c) has a residual spin solvent level of below 40 ppm. 
     
     
         13 . The process according to  claim 1 , wherein the treated filament obtained in step (c) has a tenacity of at least 3.4 N/tex. 
     
     
         14 . The process according to  claim 1 , wherein the treated filament obtained in step (c) has a creep rate, measured at 50° C. under a load so that the initial stress is 600 MPa, of less than 5·10 −6  sec−1. 
     
     
         15 . The process according to  claim 14 , wherein the treated filament has a creep rate of less than 10 −7  sec −1 . 
     
     
         16 . A treated gel spun UHMwPE filament as obtained by the process according to  claim 1 . 
     
     
         17 . A gel spun UHMwPE filament having a diameter of above 16 μm and a residual spin solvent residue of less than 60 ppm. 
     
     
         18 . The gel spun UHMwPE filament according to  claim 17 , wherein the filament has a creep rate, measured at 50° C. under a load so that the initial stress is 600 MPa, of less than 5·10 −6  sec −1 . 
     
     
         19 . The gel spun UHMwPE filament according to  claim 17 , wherein the filament has a creep rate, measured at 50° C. under a load so that the initial stress is 600 MPa, of less than 8·10 −6  sec −1 . 
     
     
         20 . The gel spun UHMwPE filament according to  claim 17 , wherein the filament has a creep rate, measured at 50° C. under a load so that the initial stress is 600 MPa, of less than 10 −7  sec −1 . 
     
     
         21 . A multi-filament yarn comprising a filament according to  claim 16 . 
     
     
         22 . A mono-filament consisting of one filament according to  claim 16 . 
     
     
         23 . A product for medical application comprising the yarn according to  claim 21 . 
     
     
         24 . A product for medical application comprising the monofilament according to  claim 22 .