High-strength polyethylene yarn having an improved shrinkage rate and method for manufacturing the same
Provided are a high-strength polyethylene yarn having an improved shrinkage rate and a method for manufacturing the same. More particularly, a high-strength polyethylene yarn which has a specific microstructure and has an improved shrinkage rate to allow manufacture of high-density fabric, and a method for manufacturing the same are provided.
1 . A polyethylene yarn having a ratio (A/B) of a highest intensity peak (A) occurring at a scattering vector of 0 to 0.04 Å −1 to a highest intensity peak (B) occurring at a scattering vector of 0.05 to 0.08 Å −1 in small-angle X-ray scattering (SAXS) of 16 or more and a shrinkage rate of 2.5% or more, and a weight average molecular weight (Mw) of 200,000 to 600,000 g/mol.
2 . The polyethylene yarn of claim 1 , wherein the yarn has a melt index (MI) of 0.3 to 6 g/10 min as measured at 190° C. and 2.16 kg.
3 . The polyethylene yarn of claim 1 , wherein the yarn has a molecular weight distribution of more than 5 and less than 9.
4 . The polyethylene yarn of claim 1 , wherein the yarn has a crystallinity of 65 to 85%.
5 . The polyethylene yarn of claim 1 , wherein the yarn has a melting temperature of 130 to 140° C.
6 . The polyethylene yarn of claim 1 , wherein the yarn has a density of 0.93 to 0.97 g/cm 3 .
7 . A method for manufacturing a polyethylene yarn, the method comprising:
melting polyethylene chips having a melt index (MI) of 0.3 to 6 g/10 min as measured at 190° C. and 2.16 kg, a molecular weight distribution of more than 5 and less than 9 and a weight average molecular weight (Mw) of 200,000 to 600,000 g/mol to obtain a polyethylene melt;
spinning the polyethylene melt through a spinneret having a plurality of nozzle holes;
cooling a plurality of filaments which are formed when the polyethylene melt is discharged from the nozzle holes;
interlacing the plurality of filaments cooled to form a multifilament yarn;
drawing and heat-fixing the multifilament yarn at a total drawing ratio of 5 times to 20 times; and winding up the drawn and heat-fixed multifilament yarn,
wherein the polyethylene yarn has a ratio (A/B) of a highest intensity peak (A) occurring at a scattering vector of 0 to 0.04 Å −1 to a highest intensity peak (B) occurring at a scattering vector of 0.05 to 0.08 Å −1 in small-angle X-ray scattering (SAXS) of 16 or more and a shrinkage rate of 2.5% or more.
8 . The method for manufacturing a polyethylene yarn of claim 7 , wherein a spinning temperature of the polyethylene melt is 220 to 300° C.
9 . The method for manufacturing a polyethylene yarn of claim 7 , wherein a highest drawing temperature in the drawing is 100 to 150° C.
10 . The method for manufacturing a polyethylene yarn of claim 7 , wherein the drawing is performed as multi-stage drawing.
11 . The method for manufacturing a polyethylene yarn of claim 10 , wherein the multi-stage drawing is performed using a plurality of godet rollers.
12 . The method for manufacturing a polyethylene yarn of claim 10 , wherein the multi-stage drawing is performed in multi-stages of 4 stages or more and 20 stages or less.
13 . The method for manufacturing a polyethylene yarn of claim 11 ,
wherein the plurality of godet rollers is set to a temperature of 50 to 150° C.,
in which a temperature of a first godet roller among the plurality of godet rollers is 50 to 80° C., a temperature of a last godet roller among the plurality of godet roller parts is 100 to 150° C., and
each temperature of godet rollers other than the first and last godet rollers among the plurality of godet rollers is equivalent to or higher than a temperature of a godet roller positioned at the immediately preceding stage.