Spinning method

Abstract

A method for spinning a multifilament yarn from a thermoplastic material, where the filament bundle is cooled below the spinneret in a first cooling zone, first of all by means of at least one transverse blowing operation with a gaseous cooling medium and by means of an extraction means for the gaseous cooling medium which lies opposite said transverse blowing means, and subsequently the filament bundle is cooled further in a second cooling zone below the first cooling zone by automatic suction of gaseous cooling medium which is situated in the vicinity of the filament bundle.

1 . Polyester multifilament yarn obtained by a method for spinning a multifilament yarn from a thermoplastic material comprising the steps of extruding the melted material through a spinneret to form a filament bundle comprising a plurality of filaments and winding the filament bundle as a multifilament yarn after solidifying, said spinneret having a plurality of spinneret holes and the ends of the holes at which the filaments emerge forming a spinneret hole outlet plane, and with the filament bundle first being cooled below the spinneret in a first cooling zone by means of at least one transverse blowing operation with a gaseous cooling medium and by means of suction on the opposite side to the transverse blowing operation, and then in a second cooling zone below the first cooling zone the filament bundle being further cooled by self suction of gaseous cooling medium in the vicinity of the filament bundle, in the first cooling zone the at least one transverse blowing operation occurs via a blowing section AC of length L with the blowing section AC having an upper leading end A facing towards the spinneret holes and a lower trailing end C facing away from the spinneret holes, and that the blowing section AC is arranged opposite a section BD having a leading end B facing towards the spinneret holes and a trailing end D facing away from the spinneret holes, and that the imaginary line AB between A and B runs parallel to the spinneret hole outlet plane, with section BD having a length L and section BD being divided into an open suction section BX with the length L BX  via which the gaseous cooling medium is sucked away and a closed section XD having a length L XD , with the L BX :L XD  ratio lying in the range between 0.15:1 and 0.5:1, with a dimensional stability of not more than 11.0% and with a fluff count that is at least 5% lower than the fluff count of a polyester filament yarn spun under the same conditions, except that L BX =L. 
     
     
         2 . Polyester multifilament yarn according to  claim 1  with a dimensional stability of not more than 10.5%. 
     
     
         3 . Polyester multifilament yarn according to  claim 1  with a breaking tenacity of more than 60 cN/tex. 
     
     
         4 . Polyester multifilament yarn according to  claim 3  with a breaking tenacity of more than 65 cN/tex. 
     
     
         5 . Polyester multifilament yarn according to  claim 1  with a fluff count that is at least 50% lower than the fluff count of a polyester filament yarn spun under the same conditions, except that L BX =L. 
     
     
         6 . Polyester multifilament yarn according to  claim 5  with a fluff count that is at least 60% lower than the fluff count of a polyester filament yarn spun under the same conditions, except that L BX =L. 
     
     
         7 . Polyester multifilament yarn according to  claim 1  with a yarn breakage rate of less than 25 per 1000 kg of yarn. 
     
     
         8 . Polyester multifilament yarn according to  claim 7  with a yarn breakage rate of less than 10 per 1000 kg of yarn. 
     
     
         9 . Polyester multifilament yarn according to  claim 1 , wherein the yarn has a breaking tenacity T in mN/tex and an elongation at break E in %, whereby the product of the breaking tenacity T and the cube root of the elongation at rupture E, T·E 1/3 , is at least 1600 mN % 1/3 /tex. 
     
     
         10 . Undipped cord comprising a polyester multifilament yarn according to  claim 9 , wherein the cord has a value of at least 1375 mN % 1/3 /tex for the product T·E 1/3 . 
     
     
         11 . Dipped cord comprising a polyester multifilament yarn according to  claim 9 , said cord having a retention capacity Rt, wherein the quality factor Q f , i.e. the product of T·E 1/3  of the polyester multifilament yarn and Rt of the cord, is higher than 1350 mN % 1/3 /tex.