Raw yarn for air bag and method for producing the raw yarn

Abstract

A yarn for air bags including polyamide multifilament with a total fineness of 200 to 700 dtex, a single fiber fineness of 1 to 2 dtex, strength of 7 to 10 cN/dtex, and elongation of 20 to 30%.

1 . A yarn for air bags comprising polyamide multifilament with a total fineness of 200 to 700 dtex, a single fiber fineness of 1 to 2 dtex, strength of 7 to 10 cN/dtex, and elongation of 20 to 30%. 
     
     
         2 . The yarn as claimed in  claim 1 , wherein the polyamide is polyhexamethylene adipamide with a sulfuric acid relative viscosity of 3 to 4. 
     
     
         3 . The yarn as claimed in  claim 1 , wherein fineness unevenness is 0.5 to 1.5%. 
     
     
         4 . A method for producing the yarn as claimed in  claim 1 , wherein polyamide is melt-spun, cooled with circular cooling equipment, and then stretched. 
     
     
         5 . The method as claimed in  claim 4 , wherein fiber extruded from a spinning orifice after being melt-spun is supplied with steam and then passed through a slow cooling cylinder. 
     
     
         6 . The method as claimed in  claim 5 , wherein the slow cooling cylinder has a length of 30 to 150 mm and the circular cooling equipment has a cooling air blowout length of 600 to 1,200 mm. 
     
     
         7 . The method of  claim 4 , wherein the difference between internal pressure in the cooling cylinder of the circular cooling equipment and atmospheric pressure is 500 to 1200 Pa. 
     
     
         8 . The method of  claim 4 , wherein air speed cooling air is nonuniform along a length direction of the circular cooling equipment, upper side air speed V U  being smaller than lower side air speed V L , and values of V  L/ V U , V U , and V L  being 2 to 3, 10 to 30 m/min, and 40 to 80 m/min, respectively. 
     
     
         9 . The method of  claim 5 , wherein steam blowout pressure is 100 to 600 Pa.