Nonwoven Fabrics with Improved Haptics and Mechanical Properties

Abstract

A multicomponent fiber for nonwovens and methods for making and using same. The multicomponent fiber can include a first component comprising a first polypropylene having a MFR of at least 30 dg/min and a second polypropylene having a MFR of less than 20 dg/min. The multicomponent fiber can further include a second component comprising the first polypropylene and at least one propylene-based elastomer comprising propylene and about 10 wt % to about 30 wt % of one or more alpha-olefin derived units, based on a total weight of the elastomer, wherein the propylene-based elastomer has a MFR of at least 40 dg/min and a heat of fusion (Hi) of about 3 J/g to about 75 J/g, as determined by DSC.

1 . A multicomponent fiber for nonwovens, comprising:
 a first fiber component comprising a first polypropylene having a MFR of at least 30 dg/min and a second polypropylene having a MFR of less than 20 dg/min; and   a second fiber component comprising the first polypropylene and at least one propylene-based elastomer comprising propylene and about 10 wt % to about 30 wt % of one or more alpha-olefin derived units, based on a total weight of the elastomer, wherein the propylene-based elastomer has a MFR of at least 40 dg/min and a heat of fusion (Hf) of about 3 J/g to about 75 J/g, as determined by DSC.   
     
     
         2 . The fiber of  claim 1 , wherein the first polypropylene has a MFR of 30 dg/min to about 40 dg/min. 
     
     
         3 . The fiber of  claim 1 , wherein the first polypropylene has a melt temperature (Tm) of at least 140° C. 
     
     
         4 . The fiber of  claim 1 , wherein the second polypropylene has a melt temperature (Tm) of at least 140° C. 
     
     
         5 . The fiber of  claim 1 , wherein the second polypropylene has a MFR of 10 dg/min to about 20 dg/min. 
     
     
         6 . The fiber of  claim 1 , wherein the second polypropylene has a MFR that is less than half the MFR of the first polypropylene. 
     
     
         7 . The fiber of  claim 1 , wherein the second polypropylene has a MFR that is 15% to 40% of the MFR of the first polypropylene. 
     
     
         8 . The fiber of  claim 1 , wherein at least one propylene-based elastomer has a MFR of 40 dg/min to about 60 dg/min. 
     
     
         9 . The fiber of  claim 1 , wherein the one or more alpha-olefin derived units consist essentially of ethylene. 
     
     
         10 . The fiber of  claim 1 , wherein the one or more alpha-olefin derived units consists of ethylene. 
     
     
         11 . The fiber of  claim 1 , wherein the at least one propylene-based elastomer has a tacticity index (m/r) of 4 to 12. 
     
     
         12 . The fiber of  claim 1 , wherein the at least one propylene-based elastomer has a density of about 0.84 g/cm 3  to about 0.92 g/cm 3 . 
     
     
         13 . The fiber of  claim 1 , wherein the at least one propylene-based elastomer has a percent crystallinity of about 1% to about 40%. 
     
     
         14 . The fiber of  claim 1 , wherein a ratio of the first polypropylene to the propylene-based elastomer in the second fiber component ranges from 5/95 to 95/5. 
     
     
         15 . The fiber of  claim 1 , wherein a ratio of the first polypropylene to the second polypropylene in the first fiber component ranges from 20/80 to 80/20. 
     
     
         16 . The fiber of  claim 1 , wherein the first polypropylene is a propylene homopolymer. 
     
     
         17 . The fiber of  claim 1 , wherein herein the second polypropylene is a propylene homopolymer. 
     
     
         18 . A method for making a fiber for fabrics with suitable thickness and softness, the method comprising:
 forming a first polymer composition comprising a first polypropylene having a MFR of at least 30 dg/min and a second polypropylene having a MFR of less than 20 dg/min;   forming a second polymer composition comprising the first polypropylene and at least one propylene-based elastomer comprising propylene and about 10 wt % to about 30 wt % of one or more alpha-olefin derived units, based on a total weight of the elastomer and having a MFR of at least 40 dg/min and a heat of fusion (Hf) of about 3 J/g to about 75 J/g, as determined by DSC;   forming a plurality of fibers from the first polymer composition and the second polymer composition in a side by side configuration; and   making a fabric from the plurality of fibers, wherein the fabric has a thickness of at least 0.40 mm, a total hand of less than 20 g, and a MD and CD tensile of at least 8 N/5 cm.   
     
     
         19 . The method of  claim 18 , wherein forming fibers comprises spun-bonding the first polymer composition and the second polymer composition to form side-by-side fibers. 
     
     
         20 . The method of  claim 18 , further comprising directing the fibers to a spin-belt, laying down the fibers on the spin-belt and forming a fabric from the fibers. 
     
     
         21 . The method of  claim 18 , wherein a ratio of the first polypropylene to the second polypropylene in the first polymer composition ranges from 20/80 to 80/20, and a ratio of the first polypropylene to the propylene-based elastomer in the second polymer composition ranges from 5/95 to 95/5. 
     
     
         22 . A hygiene product comprising the fibers of  claim 1 . 
     
     
         23 .- 30 . (canceled)