Multicomponent Biodegradable Filaments and Nonwoven Webs Formed Therefrom

Abstract

A biodegradable, substantially continuous filament is provided. The filament contains a first component formed from at least one high melting polyester and a second component formed from at least one low melting polyester. The low melting point polyester is an aliphatic-aromatic copolyester formed by melt blending a polymer and an alcohol to initiate an alcoholysis reaction that results in a copolyester having one or more hydroxyalkyl or alkyl terminal groups. By selectively controlling the alcoholysis conditions (e.g., alcohol and copolymer concentrations, catalysts, temperature, etc.), a modified aliphatic-aromatic copolyester may be achieved that has a molecular weight lower than the starting aliphatic-aromatic polymer. Such lower molecular weight polymers also have the combination of a higher melt flow index and lower apparent viscosity, which is useful in the formation of substantially continuous filaments.

1 . A biodegradable, substantially continuous multicomponent filament comprising a first component and a second component, the first component containing a first polyester having a melting point of from about 150° C. to about 250° C. and the second component containing a second polyester, wherein the second polyester is an aliphatic-aromatic copolyester terminated with an alkyl group, hydroxyalkyl group, or a combination thereof, the aliphatic-aromatic copolyester having a melt flow index of from about 5 to about 200 grams per 10 minutes, determined at a load of 2160 grams and temperature of 190° C. in accordance with ASTM Test Method D1238-E. 
     
     
         2 . The biodegradable filament of  claim 1 , wherein the melt flow index of the copolyester is from about 15 to about 50 grams per 10 minutes. 
     
     
         3 . The biodegradable filament of  claim 1 , wherein the copolyester has a number average molecular weight of from about 10,000 to about 70,000 grams per mole and a weight average molecular weight of from about 20,000 to about 125,000 grams per mole. 
     
     
         4 . The biodegradable filament of  claim 1 , wherein the copolyester has a number average molecular weight of from about 20,000 to about 60,000 grams per mole and a weight average molecular weight of from about 30,000 to about 110,000 grams per mole. 
     
     
         5 . The biodegradable filament of  claim 1 , wherein the copolyester has a melting point of from about 50° C. to about 150° C. 
     
     
         6 . The biodegradable filament of  claim 1 , wherein the copolyester has a glass transition temperature of about 0° C. or less. 
     
     
         7 . The biodegradable filament of  claim 1 , wherein the copolyester has the following general structure: 
       
         
           
           
               
               
           
         
         wherein, 
         m is an integer from 2 to 10, in some embodiments from 2 to 4, and in one embodiment, 4; 
         n is an integer from 0 to 18, in some embodiments from 2 to 4, and in one embodiment, 4; 
         p is an integer from 2 to 10, in some embodiments from 2 to 4, and in one embodiment, 4; 
         x is an integer greater than 1; 
         y is an integer greater than 1; and 
         R 1  and R 2  are independently selected from hydrogen; hydroxyl groups; straight chain or branched, substituted or unsubstituted C 1 -C 10  alkyl groups; and straight chain or branched, substituted or unsubstituted C 1 -C 10  hydroxalkyl groups. 
       
     
     
         8 . The biodegradable filament of  claim 7 , wherein m and n are each from 2 to 4. 
     
     
         9 . The biodegradable filament of  claim 7 , wherein the copolyester is derived from polybutylene adipate terephalate. 
     
     
         10 . The biodegradable filament of  claim 1 , wherein the first polyester is polylactic acid. 
     
     
         11 . The biodegradable filament of  claim 1 , wherein the filament has a sheath/core or side-by-side configuration. 
     
     
         12 . A nonwoven web comprising the biodegradable filament of  claim 1 . 
     
     
         13 . An absorbent article comprising an absorbent core positioned between a substantially liquid-impermeable layer and a liquid-permeable layer, wherein the substantially liquid-impermeable layer contains the nonwoven web of  claim 12 . 
     
     
         14 . The absorbent article of  claim 13 , wherein the substantially liquid-impermeable layer forms an outer cover of the absorbent article. 
     
     
         15 . The absorbent article of  claim 14 , wherein the nonwoven web is laminated to a breathable film. 
     
     
         16 - 37 . (canceled)