Super-high-molecular-weight polyolefin yarn, method for producing same, and drawing device

Abstract

An ultrahigh molecular weight polyolefin yarn of the present invention has been drawn and has a melting point that is determined as a maximum peak temperature measured by a differential scanning calorimeter (DSC) at a temperature rise rate of 20° C./min, and the melting point is higher than a melting point of the yarn before drawing. In a production method of the present invention, a drawing bath ( 3 ) that includes a hollow yarn path ( 14 ) and a jacket portion ( 13 ) in which a heated liquid circulates is placed in a drawing zone, and the yarn is heated and drawn while passing through the yarn path ( 14 ) in a non-contact manner. A drawing device of the present invention includes a feeder ( 1 ) for feeding a yarn, a drawing bath ( 3 ) for heating and drawing the yarn, and a winder ( 5 ) for winding up the drawn yarn. The drawing bath ( 3 ) includes a hollow yarn path ( 14 ) and a jacket portion ( 13 ) in which a heated liquid circulates. Thus, the present invention provides a drawing method in which a high strength ultrahigh molecular weight polyolefin yarn can be drawn stably even at a high draw ratio, a drawing device, and a yarn obtained by the drawing method.

1 . An ultrahigh molecular weight polyolefin yarn that has been drawn, having a melting point that is determined as a maximum peak temperature measured by a differential scanning calorimeter (DSC) at a temperature rise rate of 20° C./min in an unconstrained state,
 wherein the melting point is higher than a melting point of the yarn before drawing. 
 
     
     
         2 . The ultrahigh molecular weight polyolefin yarn according to  claim 1 , wherein the melting point of the drawn ultrahigh molecular weight polyolefin yarn is at least 5° C. higher than the melting point of the yarn before drawing. 
     
     
         3 . The ultrahigh molecular weight polyolefin yarn according to  claim 1 , wherein the drawn ultrahigh molecular weight polyolefin yarn has a total fineness of 50 dtex or less and a coefficient of variation in strength of 2% or less. 
     
     
         4 . The ultrahigh molecular weight polyolefin yarn according to  claim 1 , wherein the ultrahigh molecular weight polyolefin is ultrahigh molecular weight polyethylene. 
     
     
         5 . The ultrahigh molecular weight polyolefin yarn according to  claim 4 , wherein the ultrahigh molecular weight polyethylene yarn has been drawn and has a maximum melting peak temperature of 155 to 162° C., which is measured by a differential scanning calorimeter (DSC) at a temperature rise rate of 20° C./min in an unconstrained state. 
     
     
         6 . The ultrahigh molecular weight polyolefin yarn according to  claim 4 , wherein the drawn ultrahigh molecular weight polyethylene yarn has a degree of crystallinity of 76 to 85%, which is determined from heat of fusion measured by a differential scanning calorimeter (DSC) at a temperature rise rate of 20° C./min in an unconstrained state. 
     
     
         7 . A method for producing an ultrahigh molecular weight polyolefin yarn comprising:
 heating and drawing the ultrahigh molecular weight polyolefin yarn,   wherein a drawing bath that includes a hollow yarn path and a jacket portion in which a heated liquid circulates is placed in a drawing zone,   positive air ventilation is not provided in the yarn path, and the yarn is heated by radiant heat from the jacket portion and natural convection,   an ambient temperature of the drawing bath is 150 to 157° C. and is controlled within ±0.2° C., and the yarn is heated and drawn while passing through the yarn path in a non-contact manner.   
     
     
         8 . (canceled) 
     
     
         9 . The method for producing an ultrahigh molecular weight polyolefin yarn according to  claim 7 , wherein a draw ratio in the drawing zone is 1.5 to 10 times. 
     
     
         10 . (canceled) 
     
     
         11 . The method for producing an ultrahigh molecular weight polyolefin yarn according to  claim 7 , wherein the yarn before drawing is an untwisted yarn, an interlaced yarn, a twisted yarn, or a braided yarn. 
     
     
         12 . The method for producing an ultrahigh molecular weight polyolefin yarn according to  claim 7 , wherein the yarn before drawing has a fineness of 400 dtex or less. 
     
     
         13 . A method for producing an ultrahigh molecular weight polyolefin yarn comprising:
 drawing a raw yarn before braiding by the drawing process according to  claim 7 ; and   subsequently braiding at least part of the drawn yarn.   
     
     
         14 . A method for producing an ultrahigh molecular weight polyolefin yarn comprising:
 drawing a raw yarn before braiding by the drawing process according to  claim 7 ;   subsequently braiding at least part of the drawn yarn; and   further drawing the braided yarn.   
     
     
         15 . A drawing device used in the method for producing an ultrahigh molecular weight polyolefin yarn according to  claim 7 , comprising:
 a feeder for feeding a yarn;   a drawing bath for heating and drawing the yarn;   a winder for winding up the drawn yarn,   wherein the drawing bath includes a hollow yarn path and a jacket portion in which a heated liquid circulates.   
     
     
         16 . The drawing device according to  claim 15 , wherein the heated liquid is heated outside the drawing bath, and is circulated by a pump. 
     
     
         17 . The drawing device according to  claim 15 , wherein the yarn path has a height or diameter of 5 to 300 mm, and the drawing bath has a length of 0.3 to 10 m.