Strong Elastic Bicomponent Fiber Having Unique Handfeel

Abstract

An elastomeric bicomponent fiber, including at least one sheath and a core, with non-blocking properties and a garment-like feel is provided. The core includes two or more polypropylene based elastomers and a secondary amide, and the sheath includes a non-elastomeric polyethylene. Further, the sheath can be present as a small portion of the total elastomeric composition, and the secondary amide can be present as a small portion of the core, while forming a bicomponent fiber with non-blocking properties and a garment-like feel, while maintaining good strength characteristics.

What is claimed: 
     
         1 . A nonwoven web comprising an elastomeric bicomponent fiber, the elastomeric bicomponent fiber comprising:
 a core comprising at least two polypropylene based elastomers and a secondary amide; and   at least one sheath;   wherein the at least one sheath comprises less than 50 wt. % of the total weight of the bicomponent fiber; and   wherein the nonwoven web exhibits a peak burst load of about 1100 gf or greater based upon a nonwoven web having a basis weight of about 48 grams per square meter (gsm) or a normalized peak burst load of about 22 gf/gsm.   
     
     
         2 . The nonwoven web of  claim 1 , wherein the nonwoven web exhibits a cup crush bending stiffness of about 100 gf or less based upon a nonwoven web having a basis weight of about 48 grams per square meter (gsm) or a normalized cup crush bending stiffness of about 2.1 gf/gsm or less. 
     
     
         3 . The nonwoven web of  claim 1 , wherein the nonwoven web exhibits an effusivity of about 90 Ws 1/2 /m 2 K or greater. 
     
     
         4 . The nonwoven web of  claim 1 , wherein the at least two polypropylene based elastomers comprise an ethylene copolymer, α-olefin copolymer, or a combination thereof. 
     
     
         5 . The nonwoven web of  claim 1 , wherein the sheath comprises a non-elastomeric polymer. 
     
     
         6 . The nonwoven web of  claim 1 , wherein the sheath comprises a polyethylene polymer. 
     
     
         7 . The nonwoven web of  claim 1 , wherein the secondary amide is present in the core in an amount of about 0.1% to about 10% by weight based upon the weight of the core. 
     
     
         8 . The nonwoven web of  claim 1 , wherein the secondary amide is present in the core in an amount of about 0.25% to about 5% by weight based upon the weight of the core. 
     
     
         9 . The nonwoven web of  claim 1 , wherein the secondary amide is a fatty acid amide. 
     
     
         10 . The nonwoven web of  claim 1 , wherein the at least two polypropylene based elastomer comprise a propylene/ethylene copolymer. 
     
     
         11 . The nonwoven web of  claim 1 , wherein at least one of the sheath and the core further comprises pigment particles. 
     
     
         12 . The nonwoven web of  claim 1 , wherein the pigment particles are present in the at least one of the sheath and the core in an amount of about 0.1% to about 5% by weight based upon the weight of the sheath or the core. 
     
     
         13 . The nonwoven web of  claim 1 , wherein the core further comprises about 5 wt. % or less of a polypropylene homopolymer, based upon the weight of the core. 
     
     
         14 . An elastomeric laminate comprising a spunbond nonwoven web according to  claim 1 , and a backing. 
     
     
         15 . The elastomeric laminate of  claim 14 , wherein the backing comprises an elastic film. 
     
     
         16 . An absorbent article formed from the nonwoven web of  claim 1 . 
     
     
         17 . An elastomeric bicomponent fiber comprising:
 a core comprising at least two polypropylene based elastomers and a secondary amide; and   at least one sheath;   wherein the at least one sheath comprises less than 50 wt. % of the total weight of the bicomponent fiber; and   wherein the elastomeric bicomponent fiber exhibits a FTIR peak height ratio of an 842 cm −1  peak to an 974 cm −1  peak of about 0.525 or greater, as measured using a Perkin Elmer Frontier FTIR spectrometer, based upon an average of 32 scans at 4 cm −1  resolution.   
     
     
         18 . The elastomeric bicomponent fiber of  claim 17 , wherein the at least two polypropylene based elastomers include a first polypropylene based elastomer and a second polypropylene based elastomer, wherein the first polypropylene based elastomer comprises about 30 wt. % or more of the core, based upon the weight of the core. 
     
     
         19 . The elastomeric bicomponent fiber of  claim 18 , wherein the second polypropylene based elastomer comprises about 60 wt. % or less of the core, based upon the weight of the core. 
     
     
         20 . The elastomeric bicomponent fiber of  claim 17 , wherein the core further comprises about 15 wt. % or less of a polypropylene homopolymer.