Conjugate fiber having low-temperature processability, nonwoven fabric and formed article using the conjugate fiber

Abstract

To provide a conjugate fiber that demonstrates low-temperature processability and excellent thermal adhesiveness without shrinking significantly, can be processed with excellent card passability when processed into a nonwoven fabric, and can produce a bulky nonwoven fabric having excellent uniformity. Bulky nonwoven fabric and a formed article having excellent low-temperature processability and excellent feeling are also provided. A conjugate fiber in which a first component that contains at least 75% by weight of an ethylene α-olefin copolymer having a melting point of 70 to 100° C. and a second component that contains a crystalline polypropylene form a side-by-side cross section, wherein, in a fiber cross section perpendicular to a fiber axis, the first component accounts for 55 to 90% of an outer periphery of the fiber, a borderline between the first component and the second component forms a curve bulging toward the first component, and an area ratio between the first component and the second component (first component/second component) is in a range of 70/30 to 30/70; a nonwoven fabric obtained by processing the conjugate fiber into a nonwoven fabric; and a formed article obtained using the conjugate fiber.

1 . A conjugate fiber in which a first component that contains at least 75% by weight of an ethylene α-olefin copolymer having a melting point of 70 to 100° C. and a second component that contains a crystalline polypropylene form a side-by-side cross section, wherein, in a fiber cross section perpendicular to a fiber axis, the first component accounts for 55 to 90% of an outer periphery of the fiber, a borderline between the first component and the second component forms a curve bulging toward the first component, and an area ratio between the first component and the second component (first component/second component) is in a range of 70/30 to 30/70. 
     
     
         2 . The conjugate fiber according to  claim 1 , wherein the ethylene α-olefin copolymer has a molecular weight distribution (Mw/Mn) of 1.5 to 2.5, a density of 0.87 to 0.91 g/cm 3 , and a melt index (MI) of 10 to 35 g/10 min as measured under conditions with a temperature of 190° C. and a load of 21.2 N based on ASTM D-1238. 
     
     
         3 . The conjugate fiber according to  claim 1 , wherein a heat shrinkage percentage thereof that is obtained when subjected to heat processing at 100° C. for five minutes is 50% or lower. 
     
     
         4 . A nonwoven fabric, which is obtained by processing the conjugate fiber described in  claim 1  into a nonwoven fabric. 
     
     
         5 . The nonwoven fabric according to  claim 4 , wherein the conjugate fiber is processed into a nonwoven fabric by a hot-air adhesion method or a hot-water adhesion method. 
     
     
         6 . A formed article, which is obtained by using the conjugate fiber described in  claim 1 . 
     
     
         7 . A formed article, which is obtained by using the nonwoven fabric described in  claim 4 .