Multicomponent aliphatic polyester blend fibers

Abstract

The present invention provides multicomponent thermoplastic fibers that are biodegradable and that are capable of forming strong bonds in air bonding processes. In various embodiments, the multicomponent fibers can include a first polymer component that includes a first aliphatic polyester, and a second polymer component also including an aliphatic polyester, wherein the first polymer component comprises at least a portion of an exposed surface of the multicomponent fiber. The first polymer component can be a fully amorphous polylactic acid and the second polymer component can be a semicrystalline polylactic acid. The multicomponent fiber can have cross-sectional area comprising the first polymer component and the second polymer component in about a 1:1 ratio, wherein the first polymer component and the second polymer component are configured in a sheath/core arrangement.

1 . A multicomponent fiber having an exposed surface comprising:
 a first polymer component comprising a first aliphatic polyester, wherein the first polymer component forms at least a portion of the exposed surface of the multicomponent fiber; and   a second polymer component comprising a second aliphatic polyester;   wherein about 5% or greater of the exposed surface of the multicomponent fiber is defined by the first polymer component; and   wherein the multicomponent fiber has a cross-sectional area comprising the first polymer component and the second polymer component in a ratio of about 1:9 to about 9:1.   
     
     
         2 . The multicomponent fiber of  claim 1 , wherein the fiber is selected from the group consisting of continuous filaments, staple fibers, spunbond, and meltblown fibers. 
     
     
         3 . The multicomponent fiber of  claim 1 , wherein the first polymer component is polylactic acid. 
     
     
         4 . The multicomponent fiber of  claim 1 , wherein the first polymer component comprises a fully amorphous polylactic acid having a D-isomer content of about 5% or greater. 
     
     
         5 . The multicomponent fiber of  claim 1 , wherein the first polymer component comprises an additive adapted to reduce the bonding temperature of the first polymer component, wherein the additive is present in an amount sufficient to reduce the bonding temperature of the first polymer component by about 10° C. or more. 
     
     
         6 . The multicomponent fiber of  claim 1 , wherein the first polymer component is defined by a first molecular weight, and wherein the first polymer component comprises an additive in an amount sufficient to reduce the first molecular weight to a first reduced molecular weight. 
     
     
         7 . The multicomponent fiber of  claim 6 , wherein the first reduced molecular weight is less than the first molecular weight by about 10% or more. 
     
     
         8 . The multicomponent fiber of  claim 6 , wherein the ratio of the first reduced molecular weight to the first molecular weight is about 0.9 or less. 
     
     
         9 . The multicomponent fiber of  claim 9 , wherein the additive is selected from the group consisting of pentaerythritol, water, sodium hydroxide, hydrated alumina trihydrate, ethylene glycol, and combinations thereof. 
     
     
         10 . The multicomponent fiber of  claim 9 , wherein the first polymer component comprises about 0.5% to about 8.0% by weight of pentaerythritol. 
     
     
         11 . The multicomponent fiber of  claim 1 , wherein the first polymer component has a melt flow index of about 30 or greater when evaluated according to melt flow test ASTM D1238 at a temperature 210° C. and using a 2160 g basis weight. 
     
     
         12 . The multicomponent fiber of  claim 1 , wherein the second polymer component is polylactic acid. 
     
     
         13 . The multicomponent fiber of  claim 1 , wherein the second polymer component comprises a semicrystalline polylactic acid having a D-isomer content of about 2% or less. 
     
     
         14 . The multicomponent fiber of  claim 1 , wherein the second polymer component has a melt temperature of about 160° C. or greater. 
     
     
         15 . The multicomponent fiber of  claim 1 , wherein the first polymer component is defined by a first molecular weight, wherein the second polymer component is defined by a second molecular weight, and wherein the ratio of the first molecular weight to the second molecular weight is about 0.9 or less. 
     
     
         16 . The multicomponent fiber of  claim 1 , wherein the fiber exhibits a shrinkage of less than 20% after exposure to a temperature of 130° C. for 5 minutes. 
     
     
         17 . The multicomponent fiber of  claim 1 , wherein the fiber is adapted to impart a bonded web strength of about 150 grams force or greater for a bonded nonwoven comprising the multicomponent fiber as the sole bonding agent, wherein the bonded web strength is evaluated in relation to a carded nonwoven web of 75% PLA 6202D fiber and 25% by weight of the multicomponent fiber, the web having a length of about 1.5 inches, a width of about 2 inches, and a weight of about 0.1 to about 0.3 grams, and the web being air bonded with a 12 second residence time in a bonding oven at a temperature of 130° C. 
     
     
         18 . A fabric comprising a plurality of thermally bonded multicomponent fibers according to  claim 1 . 
     
     
         19 . The fabric of  claim 18 , wherein the fabric exhibits a tensile strength of about 500 grams force or greater per gram of fabric weight 
     
     
         20 . The fabric of  claim 18 , wherein the fabric exhibits a tensile strength of about 150 grams force or greater for a fabric sample having a length and width of about 1.5 inches and about 2 inches, respectively, and having a weight of about 0.1 to about 0.3 grams. 
     
     
         21 . A method of forming a nonwoven fabric comprising:
 providing a plurality of multicomponent fibers each with an exposed surface, wherein each multicomponent fiber comprises a first polymer component and a second polymer component, and wherein the first polymer component forms at least a portion of an exposed surface of each multicomponent fiber; and   thermal air bonding the plurality of multicomponent fibers, wherein the bonding is carried out at temperature of about 80° C. to about 220° C., and wherein the second polymer component has a melting temperature that is greater than the bonding temperature.