Nonwoven Webs Made from Multicomponent Filaments and Process for Forming Nonwoven Webs

Abstract

Multicomponent filaments, nonwoven webs made from the multicomponent filaments, and processes for forming nonwoven webs are disclosed. In accordance with the present invention, the multicomponent filaments contain a crimp enhancement additive. Specifically, the crimp enhancement additive is added to a polymeric component and increases the crystallization and/or solidification rate of that polymeric component. The use of the crimp enhancement additive in one of the polymeric components of the multicomponent filaments allows the multicomponent filaments to inherently crimp without the use of any post-crystallization/solidification heat treatment. The process produces webs with improved fabric density and softness properties. The crimp enhancement additive incorporated into the filaments is a polyolefin homopolymer, in particular a polypropylene homopolymer.

1 . A process for forming a nonwoven web comprising the steps of:
 melt spinning multicomponent filaments, the filaments comprising a first polymeric component and a second polymeric component, the second polymeric component having a faster solidification and/or crystallization rate than the first polymeric component, the second polymeric component containing a crimp enhancement additive, the crimp enhancement additive comprising a polyolefin homopolymer having a melt flow rate of less than about 20 g/10 min;   drawing the multicomponent filaments onto a forming surface for forming the nonwoven web; and   wherein the crimp enhancement additive causes the multicomponent filaments to inherently crimp as the filaments are solidifying and/or crystalizing.   
     
     
         2 . A process for forming a nonwoven web of  claim 1 , wherein the multicomponent filaments have an average of at least about five crimps per inch. 
     
     
         3 . (canceled) 
     
     
         4 . A process for forming a nonwoven web of  claim 1 , wherein the multicomponent filaments comprise greater than about 90% polypropylene by weight. 
     
     
         5 . (canceled) 
     
     
         6 . (canceled) 
     
     
         7 . (canceled) 
     
     
         8 . A process for forming a nonwoven web of  claim 1 , wherein the nonwoven web has a basis weight between about 10 GSM and about 60 GSM. 
     
     
         9 . A process for forming a nonwoven web of  claim 1 , wherein the crimp enhancement additive is polypropylene homopolymer. 
     
     
         10 . A process for forming a nonwoven web of  claim 1 , wherein the crimp enhancement additive is phthalate free. 
     
     
         11 . A process for forming a nonwoven web of  claim 1 , wherein the crimp enhancement additive is present in the second component in an amount between about 5% and 50% by weight based on the weight of the second component. 
     
     
         12 . (canceled) 
     
     
         13 . A process for forming a nonwoven web of  claim 1 , wherein the crimp enhancement additive has a melt flow rate (MFR) between about 8 g/10 min and about 16 g/10 min as measured at a temperature of 230° C. and a load of 2.16 kg as determined in accordance with ASTM D1238. 
     
     
         14 . A process for forming a nonwoven web of  claim 1 , wherein the rate of solidification and/or crystallization of the second component is at least about 5% faster than the rate of solidification and/or crystallization of the first component. 
     
     
         15 . (canceled) 
     
     
         16 . A process for forming a nonwoven web of  claim 1 , wherein a ratio of the first polymeric component to the second polymeric component is from about 50:50 to about 90:10 by weight. 
     
     
         17 . (canceled) 
     
     
         18 . A process for forming a nonwoven web of  claim 1 , wherein the first component comprises:
 polypropylene,   a propylene/ethylene copolymer,   a secondary fatty acid amide, and   a white pigment.   
     
     
         19 . A process for forming a nonwoven web of  claim 1 , wherein the second component comprises:
 polypropylene,   the crimp enhancement additive,   a secondary fatty acid amide, and   a white pigment.   
     
     
         20 . A process for forming a nonwoven web of  claim 1 , wherein the first component comprises:
 polypropylene,   a propylene/ethylene copolymer,   a secondary fatty acid amide, and   a white pigment; and   the second component comprises:   polypropylene,   the crimp enhancement additive,   a secondary fatty acid amide, and   a white pigment.   
     
     
         21 . A process for forming a nonwoven web of  claim 20 , wherein the white pigment is present in the first component in an amount of about 1% by weight based on the weight of the first component or wherein the white pigment is present in the second component in an amount of about 1% by weight based on the weight of the second component. 
     
     
         22 . (canceled) 
     
     
         23 . (canceled) 
     
     
         24 . A process for forming a nonwoven web of  claim 1 , wherein the nonwoven web is a spunbond web. 
     
     
         25 . A process for forming a nonwoven web of  claim 1 , wherein the multicomponent filaments are continuous. 
     
     
         26 . A process for forming a nonwoven web of  claim 1 , wherein the multicomponent filaments are discontinuous. 
     
     
         27 . A nonwoven web comprising inherently crimped multicomponent filaments that have not been heat treated, wherein the multicomponent filaments have an average of at least about five crimps per inch, wherein the multicomponent filaments comprise:
 a first component comprising:   polypropylene,   a propylene/ethylene copolymer,   a secondary fatty acid amide, and   a white pigment; and   a second component comprising:   polypropylene,   a crimp enhancement additive comprising a polyolefin homopolymer having a melt flow rate of less than about 20 g/10 min,   a secondary fatty acid amide, and   a white pigment.   
     
     
         28 . (canceled) 
     
     
         29 . A nonwoven web of  claim 27 , wherein the multicomponent filaments have a denier between about 1 and about 3. 
     
     
         30 . A nonwoven web of  claim 27 , wherein nonwoven web has a fabric density of less than about 76 kg/m3. 
     
     
         31 . (canceled) 
     
     
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         42 . A nonwoven web of claim  22 , wherein nonwoven web has a TS7 softness of about 4 or less as measured by a TSA analyzer. 
     
     
         43 . (canceled) 
     
     
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         53 . A multicomponent filament comprising a first polymeric component and a second polymeric component, the second polymeric component having a faster solidification and/or crystallization rate than the first polymeric component, the second polymeric component containing a crimp enhancement additive, wherein the multicomponent filament has inherent crimps without heat treating and wherein the multicomponent filament has an average of at least about five crimps per inch, wherein the crimp enhancement additive is a polypropylene homopolymer. 
     
     
         54 . (canceled) 
     
     
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